[4.7.2] Blueprint InstancedStaticMesh only recieves light when blueprint pivot is within light radius

Development Rendering
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1

Since one of the latest patches my scene suddenly has loads of unbuilt objects even directly after a light build. I made a test scene and found that the problem lies with InstancedStaticMeshes. The images below describe the problem.

33117-instancedstaticmesh_lightbug.jpg
33117-instancedstaticmesh_lightbug.jpg800×1731 245 KB

As I said, this has very recently started happening, perhaps as late as 4.7.2. Is this a known issue?

2

Hi Claeng,

Thank you for taking the time to put in a report, however I’m not able to reproduce this on my end. I’ll go over what I did and we can work from there to see what may be going on. :slight_smile:

In my tests I used a light with 5000 intensity and 500 radius (unless specified otherwise). My Blueprint instanced mesh is set to static and has 10 elements. The mesh used is from the starter content (Shape_Cube).

Recreation of your scene:

Light radius adjusted to 750

The furthest is well outside the radius range.

33444-1_instancedmeshlight.png
33444-1_instancedmeshlight.png964×579 366 KB

Test 1:

33445-2_test1.png
33445-2_test1.png1672×549 663 KB

Test 2:
In this example I used a wall to help bounce indirect lighting to see if this perhaps caused an issue. I didn’t see anything that would indicate it does.

33448-2_test2.jpg
33448-2_test2.jpg1846×641 108 KB

Some suggestions:

  • Try building lighting on Production and see if the error is still happening
  • Try using a different mesh for the instance. This would be the next area to look at because there could be errors with the mesh and not the process of using instances. By using a known good mesh from the starter content we can narrow down the issues. Try using the “Shape_Cube” and see if it’s throwing the same results. This can eliminate other issues while looking into this.

Let me know.

3

Hi Tim, thanks for the reply!

I created a fresh project (engine 4.7.2) with startercontent and did the simplest possible blueprint (graph in pic below). Still getting the same problem :confused:

Reprosteps:

  1. Created a blueprint called TestBP (inheriting from actor)

  2. Added component InstancedStaticMesh, setting movibility to static, and mesh to Shape_Cube

  3. Created graph as below

  4. Created empty scene

  5. Added a brush for floor and added the blueprint on top

  6. Added a default pointlight (held L and clicked it out), no changes to settings

  7. Moved pointlight making sure that it’s radius does not contain the blueprint’s pivot

  8. Baked light (tried all settings including production)

That’s it. I can also add that I get the same result regardless of what is in the base of the blueprint, as long as it is set to static.

33541-instancedstaticmesh_lightbug2.jpg
33541-instancedstaticmesh_lightbug2.jpg1764×1310 357 KB

4

Thanks! I had missed the small text on the image stating it was using construction script earlier.

I’ve reported this with two reports UE-11741 and UE-11742. The first one is a crash resulting from using instances with this all leading back the the Build Button on the tool bar there.

If you go into the build drop down and just build lighting the instance will will light correctly, however, if you just use build it will not. Finally, if using just build geometry it will cause the crash I discovered along the way.

Hopefully this will be resolved soon. I’ll update here once a fix has been submitted.

Thank you!

Tim