Object color change based on camera FOV (heatmap)

Development Programming & Scripting
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Hi, I would like to implement(or use if there is implementation already) heatmap based on camera FOV. What I mean by this is following:

  • environment (or copy of environment) start at dark blue color
  • as player move, section of environment captured by player camera increase it RGB value from blue to green, to yellow, to red - depending how long is player looking at that environment section
  • I would like to have color change relative to other object color. What I mean by this - if total length of game is 10 min and player was looking at tree for first 3 minutes, part of the tree becomes orange/red, but then player looks at the house for 7 minutes. I want captured part of the house to be red and the tree part is decreased to green/yellow
  • export final environment colors so I can analyze it

I made research on google, redidt atc. but found nothing. I’m not sure how to implement it so first of all, is something like this even possible ? If yes what’s the best approach to do it ?

PS: I’m on Linux

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A heat map something like this? Elias Wick | Thermal Vision

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No. I mean something like this UE4 Tutorial - Make a Basic Heat Map - YouTube . But not by position but by camera FOV. So the object start to became “hotter” the more you state at them.

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Do you want exactly the viewed pixels to become hotter, or is it just “each object that’s probably visible?”
E g, if a small rock is behind a big house, but in front of the camera, should the rock become redder?

If you need “visible pixels,” then you need to have a full parameterization (unique UV mapping, similar to light map UV channel) and treat the camera as a light source and accumulate non-shadowed pixels into the per-object “light map,” which will likely require custom work in the renderer and potentially also be slowish.

If you just need “objects in frustum,” then you can run a visibility query for each object in approximately the right place for each frame, and add a counter for how many frames the objects has been in frustum. You might keep a TMap<> of objects and their material instances and counts, for example. Then make a material parameter collection that contains “total number of frames,” and maybe “maximum object frame count” (for the relative bit,) and make a material parameter for the material you add to each object that you update every frame with the frame count for that object.

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