Progressive Lightmap rebakes from scratch every time I move viewport

I have to be doing something silly here, but I'm baffled nonetheless. This is in Unity 2017.3.0f3.

I'm trying out Progressive Lightmap in a small test scene with just a few objects, some static and some not.

The lightmap bakes to completion and everything looks fine, but any time I move my scene viewport (that is, just looking around, not moving even a single GameObject in the scene), the lightmap bake restarts from scratch.

I'm sure this is pilot error by me. I've tried various settings of objects and lights (mixed vs. baked mode, lightmap static vs. not, etc.) and GI modes. I've also toggled the setting for "Prioritize View" thinking maybe that was the cause. No joy.

I'm going hunting for some specific tutorials on the Progresssive Lightmapper, but I thought I'd ask on the forum concurrently, in case someone out there can give me a "DOH!!!" push in the right direction. Thanks!

 

Ah, I understand what you're saying, and perhaps my question was phrased poorly. I am seeing this behavior even if I had previously allowed the bake to completely finish. In other words, I have a completed lightmap bake, and all I am doing is changing the position of the editor camera, not moving any GameObject in the scene or changing any parameters. If lightmaps worked that way at runtime, they would be ... well, "not useful" would be an understatement.

Does that help to clarify the problem?

I've also tried to replicate this on smaller scenes, and I have found that on a very small test scene the Progressive Lightmapper works exactly as expected -- no rebakes when I move around in the editor. It's something about this one large scene that is triggering the re-bakes, and I'm not sure what that could be.

 

turn off autobake and turn it on when you need it?

 

Oh, man, would I love to do that. I'll have to try to replicate it in a separate project by copying parts of my scene. The problem is that this project is about 6 gigabytes right now, so it's probably not feasible to upload the whole project.

This may take me some time, but if you think it might actually be a bug, I'll try to do this to help pin it down. I've been assuming it was just me doing something stupid in my settings.

 

That's what I tried first, and it works after a fashion, but the bake starts entirely over from scratch every time. The Progressive bake isn't being progressive.

I'm lucky for now that I'm able to continue development with all realtime lighting, but this is a problem I'll have to solve eventually, or else resign myself to 6+ hour bakes in Enlighten.

I know Unity is working on GPU-based lightmapping...I am sooooooo eager for that, since my GPU is a GTX 1080.

 

In a related note I notice PLM jerks and pauses my editing experience on any recent build with it including 2018.1 b6. Enlighten doesn't affect the editor experience. Seems kind of missing the point of PLM if it's not really usable during it's baking.