So the setting in houdini called "aperture" that has a value of 41.4214 is really the horizontal dimension of your sensor. A full frame 35mm camera has a sensor size of 24mm x 36mm. That is why most software has 36 as the default. I was told (by different sources) the reason houdini has a value of 41.4214 is because that paired with a default 50mm lens produces a perfect 45 degree fov. If your camera has a 20mm focal range with 35mm equivalent, I suppose that means when compared to a standard 35mm sensor your focal length would be 20 mm. I would try two things and see which works better. 1. try setting the aperture value to 36 (because that matches the standard 35mm sensor size horizontal dimension) and your focal length to 20mm 2. try putting the horizontal dimension of your sensor for the aperture value (6.17 I think you said) then find what the actual focal length of your lens is (not the 35mm equiv) and use that for your focal length value. from my experience using either of those should work.

I spent time trying to figure this out a while back. First I am not sure why it is called aperture since it is really the horizontal dimension of the film sensor. What ever your sensor size is, put the horizontal dimension as the value here instead of 41.4214. if you have a full frame it would be 36. You can test this out by exporting a camera from blender or maya as a abc. They will import with a aperture of 36 mm because that is typically the default everywhere. then you can match the focal length value with the value of your camera. edit: I see you are using a camera on a drone, so I am guessing it isn't full frame. Just google the dimensions of your sensor on the camera.

this doesn't directly answer your question, but karma can do this. When using karma/solaris it saves the snap shot to disk and you can see it again when re-opening houdini. A lot of good features are being added but you have to use solaris to use them.

Not sure how to do it in mantra, but in redshift I can make a material that receives GI and shadows (and I can also disable one or both of those if I want), but not normal lighting. That way my texture matches the scene but can also pick up shadows in case a shadow is cast over it. If you can't do that in mantra it would be possible to render the geometry top faces again but with a shadow catcher material, then in compositing you comp the shadow back on the top faces as you said.

Are you using a separate material for the inner faces? That might help. I think you just don't want lighting on the top faces where your texure is being projected. The rest of the geometry needs lighting otherwise it looks flat. You just don't want lighting on the top faces so that it matches the footage. The fracture node outputs inner faces groups to help with that.

would be nice to see a more streamlined way of controlling random time offsets with point attributes. point attributes don't really work with timeshift unless in a for loop, but it doesn't work very efficiently and is really slow. CGwiki has a page about time offsets in for loops. Of course chops works, but point attribute + timeshift seems like it could be way easier.

Yea, that works for me. I wanted to see if I could boost it with a volume light. I should have clarified that.

edit: I think it just not compatible.

this isn't an answer to your question, but why not use sparse pyro?

Hello, Is it possible to have emission from pyro (fire, etc) illuminate the scene in karma? It doesn't seem that volume light works in karma. Thanks

I was told on sidefx.com forums the play bar cannot be changed in size

been using houdini for years and I never tried to do this until now. how do I make the play bar area taller/resize it? Can't really find a way to do it. thanks : )

that is what I wound up doing. I stupidly put a rs multiply node, then it came out gray. After a few mins I realized it needed a rs multiply vector, lol. I forgot sometimes rs nodes split things like that up.

update: someone pointed out to me that you can just multiply your albedo by the occlusion. You could do that either in the material or in photo shop/after effects layer the occlusion pass on top and set it to multiply. Then it looks correct.

well, I actually found the answer to my question by editing the material in mixer. I think the problem is quixel materials are meant for games, so they include a "occlusion" texture. If I disable it, it looks like my render. Of course there is no way to plug in a occlusion texture into a rs material or principled shader. So what exactly am I supposed to do to get this looking good in houdini?