Convert all .proto files to proto3 syntax. (#653)

[RFC=0000](https://github.com/googlecartographer/rfcs/blob/master/text/0000-proto3-transition.md)

cartographer/common/proto/ceres_solver_options.proto

@@ -12,14 +12,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.common.proto;
 
 message CeresSolverOptions {
   // Configure the Ceres solver. See the Ceres documentation for more
   // information: https://code.google.com/p/ceres-solver/
-  optional bool use_nonmonotonic_steps = 1;
-  optional int32 max_num_iterations = 2;
-  optional int32 num_threads = 3;
+  bool use_nonmonotonic_steps = 1;
+  int32 max_num_iterations = 2;
+  int32 num_threads = 3;
 }

cartographer/ground_truth/proto/relations.proto

@@ -12,19 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.ground_truth.proto;
 
 import "cartographer/transform/proto/transform.proto";
 
 message Relation {
-  optional int64 timestamp1 = 1;
-  optional int64 timestamp2 = 2;
+  int64 timestamp1 = 1;
+  int64 timestamp2 = 2;
 
   // The 'expected' relative transform of the tracking frame from 'timestamp2'
   // to 'timestamp1'.
-  optional transform.proto.Rigid3d expected = 3;
+  transform.proto.Rigid3d expected = 3;
 }
 
 message GroundTruth {

cartographer/mapping/proto/connected_components.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 

cartographer/mapping/proto/map_builder_options.proto

@@ -12,17 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/mapping/proto/sparse_pose_graph_options.proto";
 
 package cartographer.mapping.proto;
 
 message MapBuilderOptions {
-  optional bool use_trajectory_builder_2d = 1;
-  optional bool use_trajectory_builder_3d = 2;
+  bool use_trajectory_builder_2d = 1;
+  bool use_trajectory_builder_3d = 2;
 
   // Number of threads to use for background computations.
-  optional int32 num_background_threads = 3;
-  optional SparsePoseGraphOptions sparse_pose_graph_options = 4;
+  int32 num_background_threads = 3;
+  SparsePoseGraphOptions sparse_pose_graph_options = 4;
 }

cartographer/mapping/proto/serialization.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 
@@ -22,24 +22,24 @@ import "cartographer/mapping/proto/trajectory_node_data.proto";
 import "cartographer/sensor/proto/sensor.proto";
 
 message Submap {
-  optional SubmapId submap_id = 1;
-  optional Submap2D submap_2d = 2;
-  optional Submap3D submap_3d = 3;
+  SubmapId submap_id = 1;
+  Submap2D submap_2d = 2;
+  Submap3D submap_3d = 3;
 }
 
 message Node {
-  optional NodeId node_id = 1;
-  optional TrajectoryNodeData node_data = 5;
+  NodeId node_id = 1;
+  TrajectoryNodeData node_data = 5;
 }
 
 message ImuData {
-  optional int32 trajectory_id = 1;
-  optional sensor.proto.ImuData imu_data = 2;
+  int32 trajectory_id = 1;
+  sensor.proto.ImuData imu_data = 2;
 }
 
 message SerializedData {
-  optional Submap submap = 1;
-  optional Node node = 2;
-  optional ImuData imu_data = 3;
+  Submap submap = 1;
+  Node node = 2;
+  ImuData imu_data = 3;
   // TODO(whess): Add odometry.
 }

cartographer/mapping/proto/sparse_pose_graph.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 
@@ -20,13 +20,13 @@ import "cartographer/mapping/proto/trajectory.proto";
 import "cartographer/transform/proto/transform.proto";
 
 message SubmapId {
-  optional int32 trajectory_id = 1;
-  optional int32 submap_index = 2;  // Submap index in the given trajectory.
+  int32 trajectory_id = 1;
+  int32 submap_index = 2;  // Submap index in the given trajectory.
 }
 
 message NodeId {
-  optional int32 trajectory_id = 1;
-  optional int32 node_index = 2;  // Node index in the given trajectory.
+  int32 trajectory_id = 1;
+  int32 node_index = 2;  // Node index in the given trajectory.
 }
 
 message SparsePoseGraph {
@@ -39,16 +39,16 @@ message SparsePoseGraph {
       INTER_SUBMAP = 1;
     }
 
-    optional SubmapId submap_id = 1;  // Submap ID.
-    optional NodeId node_id = 2;  // Node ID.
+    SubmapId submap_id = 1;  // Submap ID.
+    NodeId node_id = 2;  // Node ID.
     // Pose of the node relative to submap, i.e. taking data from the node frame
     // into the submap frame.
-    optional transform.proto.Rigid3d relative_pose = 3;
+    transform.proto.Rigid3d relative_pose = 3;
     // Weight of the translational part of the constraint.
-    optional double translation_weight = 6;
+    double translation_weight = 6;
     // Weight of the rotational part of the constraint.
-    optional double rotation_weight = 7;
-    optional Tag tag = 5;
+    double rotation_weight = 7;
+    Tag tag = 5;
   }
 
   repeated Constraint constraint = 2;

cartographer/mapping/proto/sparse_pose_graph_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 
@@ -22,37 +22,37 @@ import "cartographer/mapping/sparse_pose_graph/proto/optimization_problem_option
 message SparsePoseGraphOptions {
   // Online loop closure: If positive, will run the loop closure while the map
   // is built.
-  optional int32 optimize_every_n_scans = 1;
+  int32 optimize_every_n_scans = 1;
 
   // Options for the constraint builder.
-  optional mapping.sparse_pose_graph.proto.ConstraintBuilderOptions
+  mapping.sparse_pose_graph.proto.ConstraintBuilderOptions
       constraint_builder_options = 3;
 
   // Weight used in the optimization problem for the translational component of
   // non-loop-closure scan matcher constraints.
-  optional double matcher_translation_weight = 7;
+  double matcher_translation_weight = 7;
 
   // Weight used in the optimization problem for the rotational component of
   // non-loop-closure scan matcher constraints.
-  optional double matcher_rotation_weight = 8;
+  double matcher_rotation_weight = 8;
 
   // Options for the optimization problem.
-  optional mapping.sparse_pose_graph.proto.OptimizationProblemOptions
+  mapping.sparse_pose_graph.proto.OptimizationProblemOptions
       optimization_problem_options = 4;
 
   // Number of iterations to use in 'optimization_problem_options' for the final
   // optimization.
-  optional int32 max_num_final_iterations = 6;
+  int32 max_num_final_iterations = 6;
 
   // Rate at which we sample a single trajectory's scans for global
   // localization.
-  optional double global_sampling_ratio = 5;
+  double global_sampling_ratio = 5;
 
   // Whether to output histograms for the pose residuals.
-  optional bool log_residual_histograms = 9;
+  bool log_residual_histograms = 9;
 
   // If for the duration specified by this option no global contraint has been
   // added between two trajectories, loop closure searches will be performed
   // globally rather than in a smaller search window.
-  optional double global_constraint_search_after_n_seconds = 10;
+  double global_constraint_search_after_n_seconds = 10;
 }

cartographer/mapping/proto/submap.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 
@@ -22,17 +22,17 @@ import "cartographer/transform/proto/transform.proto";
 
 // Serialized state of a mapping_2d::Submap.
 message Submap2D {
-  optional transform.proto.Rigid3d local_pose = 1;
-  optional int32 num_range_data = 2;
-  optional bool finished = 3;
-  optional mapping_2d.proto.ProbabilityGrid probability_grid = 4;
+  transform.proto.Rigid3d local_pose = 1;
+  int32 num_range_data = 2;
+  bool finished = 3;
+  mapping_2d.proto.ProbabilityGrid probability_grid = 4;
 }
 
 // Serialized state of a mapping_3d::Submap.
 message Submap3D {
-  optional transform.proto.Rigid3d local_pose = 1;
-  optional int32 num_range_data = 2;
-  optional bool finished = 3;
-  optional mapping_3d.proto.HybridGrid high_resolution_hybrid_grid = 4;
-  optional mapping_3d.proto.HybridGrid low_resolution_hybrid_grid = 5;
+  transform.proto.Rigid3d local_pose = 1;
+  int32 num_range_data = 2;
+  bool finished = 3;
+  mapping_3d.proto.HybridGrid high_resolution_hybrid_grid = 4;
+  mapping_3d.proto.HybridGrid low_resolution_hybrid_grid = 5;
 }

cartographer/mapping/proto/submap_visualization.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/transform/proto/transform.proto";
 
@@ -20,8 +20,8 @@ package cartographer.mapping.proto;
 
 message SubmapList {
   message SubmapEntry {
-    optional int32 submap_version = 1;
-    optional transform.proto.Rigid3d pose = 3;
+    int32 submap_version = 1;
+    transform.proto.Rigid3d pose = 3;
   }
 
   message TrajectorySubmapList {
@@ -34,40 +34,40 @@ message SubmapList {
 message SubmapQuery {
   message Request {
     // Index into 'SubmapList.trajectory(trajectory_id).submap'.
-    optional int32 submap_index = 1;
+    int32 submap_index = 1;
     // Index into 'TrajectoryList.trajectory'.
-    optional int32 trajectory_id = 2;
+    int32 trajectory_id = 2;
   }
 
   message Response {
     // Version of the given submap, higher means newer.
-    optional int32 submap_version = 2;
+    int32 submap_version = 2;
 
     // Texture that visualizes a grid of a submap.
     message SubmapTexture {
       // GZipped map data, in row-major order, starting with (0,0). Each cell
       // consists of two bytes: value (premultiplied by alpha) and alpha.
-      optional bytes cells = 1;
+      bytes cells = 1;
 
       // Dimensions of the grid in cells.
-      optional int32 width = 2;
-      optional int32 height = 3;
+      int32 width = 2;
+      int32 height = 3;
 
       // Size of one cell in meters.
-      optional double resolution = 4;
+      double resolution = 4;
 
       // Pose of the resolution*width x resolution*height rectangle in the
       // submap frame.
-      optional transform.proto.Rigid3d slice_pose = 5;
+      transform.proto.Rigid3d slice_pose = 5;
     }
 
     // When multiple textures are present, high resolution comes first.
     repeated SubmapTexture textures = 10;
 
     // Error message in response to malformed requests.
-    optional string error_message = 8;
+    string error_message = 8;
   }
 
-  optional Request request = 1;
-  optional Response response = 2;
+  Request request = 1;
+  Response response = 2;
 }

cartographer/mapping/proto/trajectory.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 
@@ -24,24 +24,24 @@ message Trajectory {
   // NEXT_ID: 8
   message Node {
     // Index of this node within its trajectory.
-    optional int32 node_index = 7;
+    int32 node_index = 7;
 
-    optional int64 timestamp = 1;
+    int64 timestamp = 1;
 
     // Transform from tracking to global map frame.
-    optional transform.proto.Rigid3d pose = 5;
+    transform.proto.Rigid3d pose = 5;
   }
 
   message Submap {
     // Index of this submap within its trajectory.
-    optional int32 submap_index = 2;
+    int32 submap_index = 2;
 
     // Transform from submap to global map frame.
-    optional transform.proto.Rigid3d pose = 1;
+    transform.proto.Rigid3d pose = 1;
   }
 
   // ID of this trajectory.
-  optional int32 trajectory_id = 3;
+  int32 trajectory_id = 3;
 
   // Time-ordered sequence of Nodes.
   repeated Node node = 1;

cartographer/mapping/proto/trajectory_builder_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/transform/proto/transform.proto";
 import "cartographer/mapping_2d/proto/local_trajectory_builder_options.proto";
@@ -21,16 +21,16 @@ import "cartographer/mapping_3d/proto/local_trajectory_builder_options.proto";
 package cartographer.mapping.proto;
 
 message InitialTrajectoryPose {
-  optional transform.proto.Rigid3d relative_pose = 1;
-  optional int32 to_trajectory_id = 2;
-  optional int64 timestamp = 3;
+  transform.proto.Rigid3d relative_pose = 1;
+  int32 to_trajectory_id = 2;
+  int64 timestamp = 3;
 }
 
 message TrajectoryBuilderOptions {
-  optional mapping_2d.proto.LocalTrajectoryBuilderOptions
+  mapping_2d.proto.LocalTrajectoryBuilderOptions
       trajectory_builder_2d_options = 1;
-  optional mapping_3d.proto.LocalTrajectoryBuilderOptions
+  mapping_3d.proto.LocalTrajectoryBuilderOptions
       trajectory_builder_3d_options = 2;
-  optional bool pure_localization = 3;
-  optional InitialTrajectoryPose initial_trajectory_pose = 4;
+  bool pure_localization = 3;
+  InitialTrajectoryPose initial_trajectory_pose = 4;
 }

cartographer/mapping/proto/trajectory_node_data.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.proto;
 
@@ -21,12 +21,12 @@ import "cartographer/transform/proto/transform.proto";
 
 // Serialized state of a mapping::TrajectoryNode::Data.
 message TrajectoryNodeData {
-  optional int64 timestamp = 1;
-  optional transform.proto.Quaterniond gravity_alignment = 2;
-  optional sensor.proto.CompressedPointCloud
+  int64 timestamp = 1;
+  transform.proto.Quaterniond gravity_alignment = 2;
+  sensor.proto.CompressedPointCloud
       filtered_gravity_aligned_point_cloud = 3;
-  optional sensor.proto.CompressedPointCloud high_resolution_point_cloud = 4;
-  optional sensor.proto.CompressedPointCloud low_resolution_point_cloud = 5;
+  sensor.proto.CompressedPointCloud high_resolution_point_cloud = 4;
+  sensor.proto.CompressedPointCloud low_resolution_point_cloud = 5;
   repeated float rotational_scan_matcher_histogram = 6;
-  optional transform.proto.Rigid3d local_pose = 7;
+  transform.proto.Rigid3d local_pose = 7;
 }

cartographer/mapping/sparse_pose_graph.cc

@@ -42,6 +42,8 @@ SparsePoseGraph::Constraint::Tag FromProto(
       return SparsePoseGraph::Constraint::Tag::INTRA_SUBMAP;
     case proto::SparsePoseGraph::Constraint::INTER_SUBMAP:
       return SparsePoseGraph::Constraint::Tag::INTER_SUBMAP;
+    case ::google::protobuf::kint32max:
+    case ::google::protobuf::kint32min:;
   }
   LOG(FATAL) << "Unsupported tag.";
 }

cartographer/mapping/sparse_pose_graph/proto/constraint_builder_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.sparse_pose_graph.proto;
 
@@ -24,37 +24,37 @@ import "cartographer/mapping_3d/scan_matching/proto/fast_correlative_scan_matche
 message ConstraintBuilderOptions {
   // A constraint will be added if the proportion of added constraints to
   // potential constraints drops below this number.
-  optional double sampling_ratio = 1;
+  double sampling_ratio = 1;
 
   // Threshold for poses to be considered near a submap.
-  optional double max_constraint_distance = 2;
+  double max_constraint_distance = 2;
 
   // Threshold for the scan match score below which a match is not considered.
   // Low scores indicate that the scan and map do not look similar.
-  optional double min_score = 4;
+  double min_score = 4;
 
   // Threshold below which global localizations are not trusted.
-  optional double global_localization_min_score = 5;
+  double global_localization_min_score = 5;
 
   // Weight used in the optimization problem for the translational component of
   // loop closure constraints.
-  optional double loop_closure_translation_weight = 13;
+  double loop_closure_translation_weight = 13;
 
   // Weight used in the optimization problem for the rotational component of
   // loop closure constraints.
-  optional double loop_closure_rotation_weight = 14;
+  double loop_closure_rotation_weight = 14;
 
   // If enabled, logs information of loop-closing constraints for debugging.
-  optional bool log_matches = 8;
+  bool log_matches = 8;
 
   // Options for the internally used scan matchers.
-  optional mapping_2d.scan_matching.proto.FastCorrelativeScanMatcherOptions
+  mapping_2d.scan_matching.proto.FastCorrelativeScanMatcherOptions
       fast_correlative_scan_matcher_options = 9;
-  optional mapping_2d.scan_matching.proto.CeresScanMatcherOptions
+  mapping_2d.scan_matching.proto.CeresScanMatcherOptions
       ceres_scan_matcher_options = 11;
-  optional mapping_3d.scan_matching.proto.FastCorrelativeScanMatcherOptions
+  mapping_3d.scan_matching.proto.FastCorrelativeScanMatcherOptions
       fast_correlative_scan_matcher_options_3d = 10;
 
-  optional mapping_3d.scan_matching.proto.CeresScanMatcherOptions
+  mapping_3d.scan_matching.proto.CeresScanMatcherOptions
       ceres_scan_matcher_options_3d = 12;
 }

cartographer/mapping/sparse_pose_graph/proto/optimization_problem_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping.sparse_pose_graph.proto;
 
@@ -21,28 +21,28 @@ import "cartographer/common/proto/ceres_solver_options.proto";
 // NEXT ID: 13
 message OptimizationProblemOptions {
   // Scaling parameter for Huber loss function.
-  optional double huber_scale = 1;
+  double huber_scale = 1;
 
   // Scaling parameter for the IMU acceleration term.
-  optional double acceleration_weight = 8;
+  double acceleration_weight = 8;
 
   // Scaling parameter for the IMU rotation term.
-  optional double rotation_weight = 9;
+  double rotation_weight = 9;
 
   // Penalty factors for translation changes to the relative pose between consecutive scans.
-  optional double consecutive_scan_translation_penalty_factor = 2;
+  double consecutive_scan_translation_penalty_factor = 2;
 
   // Penalty factors for rotation changes to the relative pose between consecutive scans.
-  optional double consecutive_scan_rotation_penalty_factor = 3;
+  double consecutive_scan_rotation_penalty_factor = 3;
 
   // Scaling parameter for the FixedFramePose translation.
-  optional double fixed_frame_pose_translation_weight = 11;
+  double fixed_frame_pose_translation_weight = 11;
 
   // Scaling parameter for the FixedFramePose rotation.
-  optional double fixed_frame_pose_rotation_weight = 12;
+  double fixed_frame_pose_rotation_weight = 12;
 
   // If true, the Ceres solver summary will be logged for every optimization.
-  optional bool log_solver_summary = 5;
+  bool log_solver_summary = 5;
 
-  optional common.proto.CeresSolverOptions ceres_solver_options = 7;
+  common.proto.CeresSolverOptions ceres_solver_options = 7;
 }

cartographer/mapping_2d/proto/cell_limits.proto

@@ -12,11 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_2d.proto;
 
 message CellLimits {
-  optional int32 num_x_cells = 1;
-  optional int32 num_y_cells = 2;
+  int32 num_x_cells = 1;
+  int32 num_y_cells = 2;
 }

cartographer/mapping_2d/proto/local_trajectory_builder_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_2d.proto;
 
@@ -24,39 +24,39 @@ import "cartographer/mapping_2d/scan_matching/proto/real_time_correlative_scan_m
 
 message LocalTrajectoryBuilderOptions {
   // Rangefinder points outside these ranges will be dropped.
-  optional float min_range = 14;
-  optional float max_range = 15;
-  optional float min_z = 1;
-  optional float max_z = 2;
+  float min_range = 14;
+  float max_range = 15;
+  float min_z = 1;
+  float max_z = 2;
 
   // Points beyond 'max_range' will be inserted with this length as empty space.
-  optional float missing_data_ray_length = 16;
+  float missing_data_ray_length = 16;
 
   // Number of scans to accumulate into one unwarped, combined scan to use for
   // scan matching.
-  optional int32 scans_per_accumulation = 19;
+  int32 scans_per_accumulation = 19;
 
   // Voxel filter that gets applied to the range data immediately after
   // cropping.
-  optional float voxel_filter_size = 3;
+  float voxel_filter_size = 3;
 
   // Voxel filter used to compute a sparser point cloud for matching.
-  optional sensor.proto.AdaptiveVoxelFilterOptions
+  sensor.proto.AdaptiveVoxelFilterOptions
       adaptive_voxel_filter_options = 6;
 
   // Voxel filter used to compute a sparser point cloud for finding loop
   // closures.
-  optional sensor.proto.AdaptiveVoxelFilterOptions
+  sensor.proto.AdaptiveVoxelFilterOptions
       loop_closure_adaptive_voxel_filter_options = 20;
 
   // Whether to solve the online scan matching first using the correlative scan
   // matcher to generate a good starting point for Ceres.
-  optional bool use_online_correlative_scan_matching = 5;
-  optional scan_matching.proto.RealTimeCorrelativeScanMatcherOptions
+  bool use_online_correlative_scan_matching = 5;
+  scan_matching.proto.RealTimeCorrelativeScanMatcherOptions
       real_time_correlative_scan_matcher_options = 7;
-  optional scan_matching.proto.CeresScanMatcherOptions
+  scan_matching.proto.CeresScanMatcherOptions
       ceres_scan_matcher_options = 8;
-  optional mapping_3d.proto.MotionFilterOptions motion_filter_options = 13;
+  mapping_3d.proto.MotionFilterOptions motion_filter_options = 13;
 
   // Time constant in seconds for the orientation moving average based on
   // observed gravity via the IMU. It should be chosen so that the error
@@ -64,10 +64,10 @@ message LocalTrajectoryBuilderOptions {
   // the constant is reduced) and
   // 2. from integration of angular velocities (which gets worse when the
   // constant is increased) is balanced.
-  optional double imu_gravity_time_constant = 17;
+  double imu_gravity_time_constant = 17;
 
-  optional mapping_2d.proto.SubmapsOptions submaps_options = 11;
+  mapping_2d.proto.SubmapsOptions submaps_options = 11;
 
   // True if IMU data should be expected and used.
-  optional bool use_imu_data = 12;
+  bool use_imu_data = 12;
 }

cartographer/mapping_2d/proto/map_limits.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/mapping_2d/proto/cell_limits.proto";
 import "cartographer/transform/proto/transform.proto";
@@ -20,7 +20,7 @@ import "cartographer/transform/proto/transform.proto";
 package cartographer.mapping_2d.proto;
 
 message MapLimits {
-  optional double resolution = 1;
-  optional cartographer.transform.proto.Vector2d max = 2;
-  optional CellLimits cell_limits = 3;
+  double resolution = 1;
+  cartographer.transform.proto.Vector2d max = 2;
+  CellLimits cell_limits = 3;
 }

cartographer/mapping_2d/proto/probability_grid.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/mapping_2d/proto/map_limits.proto";
 
@@ -20,15 +20,15 @@ package cartographer.mapping_2d.proto;
 
 message ProbabilityGrid {
   message CellBox {
-    optional int32 max_x = 1;
-    optional int32 max_y = 2;
-    optional int32 min_x = 3;
-    optional int32 min_y = 4;
+    int32 max_x = 1;
+    int32 max_y = 2;
+    int32 min_x = 3;
+    int32 min_y = 4;
   }
 
-  optional MapLimits limits = 1;
+  MapLimits limits = 1;
   // These values are actually int16s, but protos don't have a native int16
   // type.
   repeated int32 cells = 2;
-  optional CellBox known_cells_box = 8;
+  CellBox known_cells_box = 8;
 }

cartographer/mapping_2d/proto/range_data_inserter_options.proto

@@ -12,20 +12,20 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_2d.proto;
 
 message RangeDataInserterOptions {
   // Probability change for a hit (this will be converted to odds and therefore
   // must be greater than 0.5).
-  optional double hit_probability = 1;
+  double hit_probability = 1;
 
   // Probability change for a miss (this will be converted to odds and therefore
   // must be less than 0.5).
-  optional double miss_probability = 2;
+  double miss_probability = 2;
 
   // If 'false', free space will not change the probabilities in the occupancy
   // grid.
-  optional bool insert_free_space = 3;
+  bool insert_free_space = 3;
 }

cartographer/mapping_2d/proto/submaps_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/mapping_2d/proto/range_data_inserter_options.proto";
 
@@ -20,12 +20,12 @@ package cartographer.mapping_2d.proto;
 
 message SubmapsOptions {
   // Resolution of the map in meters.
-  optional double resolution = 1;
+  double resolution = 1;
 
   // Number of scans before adding a new submap. Each submap will get twice the
   // number of scans inserted: First for initialization without being matched
   // against, then while being matched.
-  optional int32 num_range_data = 3;
+  int32 num_range_data = 3;
 
-  optional RangeDataInserterOptions range_data_inserter_options = 5;
+  RangeDataInserterOptions range_data_inserter_options = 5;
 }

cartographer/mapping_2d/scan_matching/proto/ceres_scan_matcher_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_2d.scan_matching.proto;
 
@@ -21,11 +21,11 @@ import "cartographer/common/proto/ceres_solver_options.proto";
 // NEXT ID: 10
 message CeresScanMatcherOptions {
   // Scaling parameters for each cost functor.
-  optional double occupied_space_weight = 1;
-  optional double translation_weight = 2;
-  optional double rotation_weight = 3;
+  double occupied_space_weight = 1;
+  double translation_weight = 2;
+  double rotation_weight = 3;
 
   // Configure the Ceres solver. See the Ceres documentation for more
   // information: https://code.google.com/p/ceres-solver/
-  optional common.proto.CeresSolverOptions ceres_solver_options = 9;
+  common.proto.CeresSolverOptions ceres_solver_options = 9;
 }

cartographer/mapping_2d/scan_matching/proto/fast_correlative_scan_matcher_options.proto

@@ -12,19 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_2d.scan_matching.proto;
 
 message FastCorrelativeScanMatcherOptions {
   // Minimum linear search window in which the best possible scan alignment
   // will be found.
-  optional double linear_search_window = 3;
+  double linear_search_window = 3;
 
   // Minimum angular search window in which the best possible scan alignment
   // will be found.
-  optional double angular_search_window = 4;
+  double angular_search_window = 4;
 
   // Number of precomputed grids to use.
-  optional int32 branch_and_bound_depth = 2;
+  int32 branch_and_bound_depth = 2;
 }

cartographer/mapping_2d/scan_matching/proto/real_time_correlative_scan_matcher_options.proto

@@ -12,20 +12,20 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_2d.scan_matching.proto;
 
 message RealTimeCorrelativeScanMatcherOptions {
   // Minimum linear search window in which the best possible scan alignment
   // will be found.
-  optional double linear_search_window = 1;
+  double linear_search_window = 1;
 
   // Minimum angular search window in which the best possible scan alignment
   // will be found.
-  optional double angular_search_window = 2;
+  double angular_search_window = 2;
 
   // Weights applied to each part of the score.
-  optional double translation_delta_cost_weight = 3;
-  optional double rotation_delta_cost_weight = 4;
+  double translation_delta_cost_weight = 3;
+  double rotation_delta_cost_weight = 4;
 }

cartographer/mapping_3d/proto/hybrid_grid.proto

@@ -12,12 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_3d.proto;
 
 message HybridGrid {
-  optional float resolution = 1;
+  float resolution = 1;
   // '{x, y, z}_indices[i]' is the index of 'values[i]'.
   repeated sint32 x_indices = 3 [packed = true];
   repeated sint32 y_indices = 4 [packed = true];

cartographer/mapping_3d/proto/local_trajectory_builder_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_3d.proto;
 
@@ -25,31 +25,31 @@ import "cartographer/mapping_3d/scan_matching/proto/ceres_scan_matcher_options.p
 // NEXT ID: 18
 message LocalTrajectoryBuilderOptions {
   // Rangefinder points outside these ranges will be dropped.
-  optional float min_range = 1;
-  optional float max_range = 2;
+  float min_range = 1;
+  float max_range = 2;
 
   // Number of scans to accumulate into one unwarped, combined scan to use for
   // scan matching.
-  optional int32 scans_per_accumulation = 3;
+  int32 scans_per_accumulation = 3;
 
   // Voxel filter that gets applied to the range data immediately after
   // cropping.
-  optional float voxel_filter_size = 4;
+  float voxel_filter_size = 4;
 
   // Voxel filter used to compute a sparser point cloud for matching.
-  optional sensor.proto.AdaptiveVoxelFilterOptions
+  sensor.proto.AdaptiveVoxelFilterOptions
       high_resolution_adaptive_voxel_filter_options = 5;
-  optional sensor.proto.AdaptiveVoxelFilterOptions
+  sensor.proto.AdaptiveVoxelFilterOptions
       low_resolution_adaptive_voxel_filter_options = 12;
 
   // Whether to solve the online scan matching first using the correlative scan
   // matcher to generate a good starting point for Ceres.
-  optional bool use_online_correlative_scan_matching = 13;
-  optional mapping_2d.scan_matching.proto.RealTimeCorrelativeScanMatcherOptions
+  bool use_online_correlative_scan_matching = 13;
+  mapping_2d.scan_matching.proto.RealTimeCorrelativeScanMatcherOptions
       real_time_correlative_scan_matcher_options = 14;
-  optional scan_matching.proto.CeresScanMatcherOptions
+  scan_matching.proto.CeresScanMatcherOptions
       ceres_scan_matcher_options = 6;
-  optional MotionFilterOptions motion_filter_options = 7;
+  MotionFilterOptions motion_filter_options = 7;
 
   // Time constant in seconds for the orientation moving average based on
   // observed gravity via the IMU. It should be chosen so that the error
@@ -57,10 +57,10 @@ message LocalTrajectoryBuilderOptions {
   // the constant is reduced) and
   // 2. from integration of angular velocities (which gets worse when the
   // constant is increased) is balanced.
-  optional double imu_gravity_time_constant = 15;
+  double imu_gravity_time_constant = 15;
 
   // Number of histogram buckets for the rotational scan matcher.
-  optional int32 rotational_histogram_size = 17;
+  int32 rotational_histogram_size = 17;
 
-  optional SubmapsOptions submaps_options = 8;
+  SubmapsOptions submaps_options = 8;
 }

cartographer/mapping_3d/proto/motion_filter_options.proto

@@ -12,17 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_3d.proto;
 
 message MotionFilterOptions {
   // Threshold above which a new scan is inserted based on time.
-  optional double max_time_seconds = 1;
+  double max_time_seconds = 1;
 
   // Threshold above which a new scan is inserted based on linear motion.
-  optional double max_distance_meters = 2;
+  double max_distance_meters = 2;
 
   // Threshold above which a new scan is inserted based on rotational motion.
-  optional double max_angle_radians = 3;
+  double max_angle_radians = 3;
 }

cartographer/mapping_3d/proto/range_data_inserter_options.proto

@@ -12,20 +12,20 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_3d.proto;
 
 message RangeDataInserterOptions {
   // Probability change for a hit (this will be converted to odds and therefore
   // must be greater than 0.5).
-  optional double hit_probability = 1;
+  double hit_probability = 1;
 
   // Probability change for a miss (this will be converted to odds and therefore
   // must be less than 0.5).
-  optional double miss_probability = 2;
+  double miss_probability = 2;
 
   // Up to how many free space voxels are updated for scan matching.
   // 0 disables free space.
-  optional int32 num_free_space_voxels = 3;
+  int32 num_free_space_voxels = 3;
 }

cartographer/mapping_3d/proto/submaps_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 import "cartographer/mapping_3d/proto/range_data_inserter_options.proto";
 
@@ -21,20 +21,20 @@ package cartographer.mapping_3d.proto;
 message SubmapsOptions {
   // Resolution of the 'high_resolution' map in meters used for local SLAM and
   // loop closure.
-  optional double high_resolution = 1;
+  double high_resolution = 1;
 
   // Maximum range to filter the point cloud to before insertion into the
   // 'high_resolution' map.
-  optional double high_resolution_max_range = 4;
+  double high_resolution_max_range = 4;
 
   // Resolution of the 'low_resolution' version of the map in meters used for
   // local SLAM only.
-  optional double low_resolution = 5;
+  double low_resolution = 5;
 
   // Number of scans before adding a new submap. Each submap will get twice the
   // number of scans inserted: First for initialization without being matched
   // against, then while being matched.
-  optional int32 num_range_data = 2;
+  int32 num_range_data = 2;
 
-  optional RangeDataInserterOptions range_data_inserter_options = 3;
+  RangeDataInserterOptions range_data_inserter_options = 3;
 }

cartographer/mapping_3d/scan_matching/proto/ceres_scan_matcher_options.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_3d.scan_matching.proto;
 
@@ -22,13 +22,13 @@ import "cartographer/common/proto/ceres_solver_options.proto";
 message CeresScanMatcherOptions {
   // Scaling parameters for each cost functor.
   repeated double occupied_space_weight = 1;
-  optional double translation_weight = 2;
-  optional double rotation_weight = 3;
+  double translation_weight = 2;
+  double rotation_weight = 3;
 
   // Whether only to allow changes to yaw, keeping roll/pitch constant.
-  optional bool only_optimize_yaw = 5;
+  bool only_optimize_yaw = 5;
 
   // Configure the Ceres solver. See the Ceres documentation for more
   // information: https://code.google.com/p/ceres-solver/
-  optional common.proto.CeresSolverOptions ceres_solver_options = 6;
+  common.proto.CeresSolverOptions ceres_solver_options = 6;
 }

cartographer/mapping_3d/scan_matching/proto/fast_correlative_scan_matcher_options.proto

@@ -12,34 +12,34 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.mapping_3d.scan_matching.proto;
 
 message FastCorrelativeScanMatcherOptions {
   // Number of precomputed grids to use.
-  optional int32 branch_and_bound_depth = 2;
+  int32 branch_and_bound_depth = 2;
 
   // Number of full resolution grids to use, additional grids will reduce the
   // resolution by half each.
-  optional int32 full_resolution_depth = 8;
+  int32 full_resolution_depth = 8;
 
   // Minimum score for the rotational scan matcher.
-  optional double min_rotational_score = 4;
+  double min_rotational_score = 4;
 
   // Threshold for the score of the low resolution grid below which a match is
   // not considered. Only used for 3D.
-  optional double min_low_resolution_score = 9;
+  double min_low_resolution_score = 9;
 
   // Linear search window in the plane orthogonal to gravity in which the best
   // possible scan alignment will be found.
-  optional double linear_xy_search_window = 5;
+  double linear_xy_search_window = 5;
 
   // Linear search window in the gravity direction in which the best possible
   // scan alignment will be found.
-  optional double linear_z_search_window = 6;
+  double linear_z_search_window = 6;
 
   // Minimum angular search window in which the best possible scan alignment
   // will be found.
-  optional double angular_search_window = 7;
+  double angular_search_window = 7;
 }

cartographer/sensor/proto/adaptive_voxel_filter_options.proto

@@ -12,18 +12,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.sensor.proto;
 
 message AdaptiveVoxelFilterOptions {
   // 'max_length' of a voxel edge.
-  optional float max_length = 1;
+  float max_length = 1;
 
   // If there are more points and not at least 'min_num_points' remain, the
   // voxel length is reduced trying to get this minimum number of points.
-  optional float min_num_points = 2;
+  float min_num_points = 2;
 
   // Points further away from the origin are removed.
-  optional float max_range = 3;
+  float max_range = 3;
 }

cartographer/sensor/proto/sensor.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.sensor.proto;
 
@@ -22,37 +22,37 @@ import "cartographer/transform/proto/transform.proto";
 
 // Compressed collection of a 3D point cloud.
 message CompressedPointCloud {
-  optional int32 num_points = 1;
+  int32 num_points = 1;
   repeated int32 point_data = 3 [packed = true];
 }
 
 // Proto representation of ::cartographer::sensor::ImuData.
 message ImuData {
-  optional int64 timestamp = 1;
-  optional transform.proto.Vector3d linear_acceleration = 2;
-  optional transform.proto.Vector3d angular_velocity = 3;
+  int64 timestamp = 1;
+  transform.proto.Vector3d linear_acceleration = 2;
+  transform.proto.Vector3d angular_velocity = 3;
 }
 
 // Proto representation of ::cartographer::sensor::OdometryData.
 message OdometryData {
-  optional int64 timestamp = 1;
-  optional transform.proto.Rigid3d pose = 2;
+  int64 timestamp = 1;
+  transform.proto.Rigid3d pose = 2;
 }
 
 // Proto representation of ::cartographer::sensor::FixedFramePoseData.
 message FixedFramePoseData {
-  optional int64 timestamp = 1;
-  optional transform.proto.Rigid3d pose = 2;
+  int64 timestamp = 1;
+  transform.proto.Rigid3d pose = 2;
 }
 
 // Proto representation of ::cartographer::sensor::LandmarkData.
 message LandmarkData {
   message Landmark {
-    optional bytes id = 1;
-    optional transform.proto.Rigid3d transform = 2;
-    optional double translation_weight = 3;
-    optional double rotation_weight = 4;
+    bytes id = 1;
+    transform.proto.Rigid3d transform = 2;
+    double translation_weight = 3;
+    double rotation_weight = 4;
   }
-  optional int64 timestamp = 1;
+  int64 timestamp = 1;
   repeated Landmark landmarks = 2;
 }

cartographer/transform/proto/transform.proto

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-syntax = "proto2";
+syntax = "proto3";
 
 package cartographer.transform.proto;
 
@@ -21,57 +21,57 @@ package cartographer.transform.proto;
 // mirror those used in the Eigen library.
 
 message Vector2d {
-  optional double x = 1;
-  optional double y = 2;
+  double x = 1;
+  double y = 2;
 }
 
 message Vector2f {
-  optional float x = 1;
-  optional float y = 2;
+  float x = 1;
+  float y = 2;
 }
 
 message Vector3d {
-  optional double x = 1;
-  optional double y = 2;
-  optional double z = 3;
+  double x = 1;
+  double y = 2;
+  double z = 3;
 }
 
 message Vector3f {
-  optional float x = 1;
-  optional float y = 2;
-  optional float z = 3;
+  float x = 1;
+  float y = 2;
+  float z = 3;
 }
 
 message Quaterniond {
-  optional double x = 1;
-  optional double y = 2;
-  optional double z = 3;
-  optional double w = 4;
+  double x = 1;
+  double y = 2;
+  double z = 3;
+  double w = 4;
 }
 
 message Quaternionf {
-  optional float x = 1;
-  optional float y = 2;
-  optional float z = 3;
-  optional float w = 4;
+  float x = 1;
+  float y = 2;
+  float z = 3;
+  float w = 4;
 }
 
 message Rigid2d {
-  optional Vector2d translation = 1;
-  optional double rotation = 2;
+  Vector2d translation = 1;
+  double rotation = 2;
 }
 
 message Rigid2f {
-  optional Vector2f translation = 1;
-  optional float rotation = 2;
+  Vector2f translation = 1;
+  float rotation = 2;
 }
 
 message Rigid3d {
-  optional Vector3d translation = 1;
-  optional Quaterniond rotation = 2;
+  Vector3d translation = 1;
+  Quaterniond rotation = 2;
 }
 
 message Rigid3f {
-  optional Vector3f translation = 1;
-  optional Quaternionf rotation = 2;
+  Vector3f translation = 1;
+  Quaternionf rotation = 2;
 }