Adds a system which enables exporting occupancy grids.

[arjo129]

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🎉 New feature

Closes #

Summary

Depends on: gazebosim/gz-math#685

This PR adds a system which exports occupancy grids. Currently its a work in progress. The BFS algorithm takes a fair deal of time to converge, hence writing a unit test may not make sense. We should also make a nice UI for it.

Test it

Follow the instructions in the example sdf.

The occupancy grid will be published as an image on the /scan_image topic.

To start the exploration, run the following command in a new terminal:

  gz topic -t /start_exploration -m gz.msgs.Boolean -p 'data: true'

reduced_Screencast.From.2025-08-22.13-24-20.mp4

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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[iche033]

Here's a patch to add the free_space_explorer system to bazel build. Can you add this?

bazel.patch

diff --git a/BUILD.bazel b/BUILD.bazel
index 9d6d2d9bb..01bc304ad 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -801,6 +801,26 @@ gz_sim_system_libraries(
     ],
 )
 
+gz_sim_system_libraries(
+    srcs = glob(
+        [
+            "src/systems/free_space_explorer/**/*.cc",
+            "src/systems/free_space_explorer/**/*.hh",
+        ],
+    ),
+    so_lib_name = "gz-sim-free-space_explorer--system.so",
+    static_lib_name = "gz-sim-free-space-explorer-system-static",
+    visibility = ["//visibility:public"],
+    deps = [
+        ":gz-sim",
+        "@gz-common//graphics",
+        "@gz-math",
+        "@gz-msgs//:gzmsgs_cc_proto",
+        "@gz-plugin//:register",
+        "@gz-transport",
+    ],
+)
+
 gz_sim_system_libraries(
     srcs = glob(
         [

After removing Get prefix from function names and fixing enum names, I was able to get this to build in bazel.

[azeey]

The overall feature looks great! I have some concerns about where the computation is being done. In most of our plugins, we have the pattern where we only do trivail things in message callbacks and defer expensive computation to Pre/PostUpdate calls. There also a number of style issues.

[azeey]

Looks great! Thanks for making all those changes.

Let's merge as is, but I'd ask if you can follow this up with an integration test.

Review comments have been addressed