Texture Map Detail

[BillyRaygun]

Both images have been rendered at 2550 x 1650dpi. I cropped the problem area.

As you can see, my texture map details don't render cleanly unless I zoom way in on the exact spot.

Is there a way to improve details like this and not have render times sky rocket? I'm currently using IR/LC

Bill

[dalomar_cg]

Re: Texture Map Detail

Its an Irradiance Map issue. Some time the interpolation of the points looses the very small details.

[BillyRaygun]

Re: Texture Map Detail

Thank you Dalomar. So, what is the work around? Not to use IR?

[Micha_cg]

Re: Texture Map Detail

Its an Irradiance Map issue. Some time the interpolation of the points looses the very small details.

Are you sure? From the topic name I suppose so we talk about texture sampling.

Last I rendered a train interior with a hole pattern on the ceiling for the air condition (only a black hole texture). As I rendered the image with not enough light I got much missing holes (first I tried to use the frame buffer curve to get the right exposure). Than I adjusted the lights at the scene and I got more details. The reason for the effect, if the image is darker, than Vray use less samples. So I would try to get a better sampling here. I'm not sure, but it could help to set a finer noise threshold - I use per default 0.015 and I would try 0.01. Maybe it helps to play with the image sampler adaptive QMC, for example to set 2/6 instead 1/4. Or try a fixed rate sampling. For saving rendertime you could render the whole image with standard sampling and render the small area again with stronger sampling settings.
I'm curious what best helps here. Please let us know if you find a good solution. Interesting problem.

[dalomar_cg]

Re: Texture Map Detail

Trust me...its IR

When IR goes to interpolate the points for the rest of the illumination solution, there's a tendency for small geometric details to get lost in the cuff. It tends to happen when those small geometric details are only a few pixels (or even smaller) in area, and its because the camera rays may or may not have intesected the geometry in a way that the IR interpolation is done accurately for that small geometry. That's why zooming in to the detail solves the problem as the geometry in question is much large in pixels and is much easier for IR to interpolate.

There's an easy way and a hard way to getting rid of this. The easy way is to just switch over to DMC, and depending on the nature of your project that may or may not be viable. The hard way is to start tweeking your IR settings. I would strongly suggest Detail Enhancement being part of those tweeks. Just thinking out loud, but it may be useful to look into the parts in question and use the Add to Current Map mode in order to get more IR sample points in those areas that need it. Other than that, this might benefit from adjusting thresholds, probably Normal and/or Distance to something like .01 and .35 respectively. Depending on how small the detail is you may have to increase your max rate to at least 0 and maybe 1.

[Micha_cg]

Re: Texture Map Detail

I could swear Bill used a slot texture and there is a flat plane only, no geometry gaps, no details, no shadows ...
From my experience lost IR geometry details are looking splotchy.

[thomthom]

Re: Texture Map Detail

I had the problem with a scene as well. But switching from IR to DMC didn't help. At least not my itself. Still not sure what parameters that corrected it. http://asgvis.com/index.php?option=c...=5381.msg29081

[BillyRaygun]

Re: Texture Map Detail

Thank you all for the responses.

@Micha - You are correct. No geometry. Just an isolated plane with a flat texture map. No bump.

I agree, after reading everyone's response and looking over ThomThom's link, this seems to be a real issue.

I guess I'll try all the suggests including the one from ThomThom's link.

This will make for an interesting experiment.

[dalomar_cg]

Re: Texture Map Detail

No offense, but Thomas's issue isn't really that much of an issue, and yes DMC is the fix for it. I mentioned camera rays in my previous post, which basically determines what actual point in the scene gets sampled. The problem is that the default antialiasing settings are set up for with a max rate of 2, leading to 4 actual samples (or camera rays) per pixel. With incredibly small details, it is easy for those camera rays NOT to actually intersect the part of the geometry in question. Whether its actual geometry or maps, the chance is the same, and if those camera rays don't land on it, then it won't arrive at a good solution. Increasing the number of subdivisons or max rate will cause more camera rays to be cast, and therefore more likely that the detail in question is captured.

Again, the smoothing affect of IR doesn't help this and can potentially compound the issue.