adaptive sampling - huge rendertimes caused by simple textures

[cdog]

Max doesn't expose any of the "new" (since 3 or 4 years ago) features I had high expectations for the 2013 release since Autodesk hired Master Zap but still nothing has changed.

[Zxx]

So it sounds like your texture has many details less than a pixel, yet you only want to sample once per pixel, because that is ok for you visually?

exactly

Using pyramid texture structures allows one to choose a less detailed texture map, if the filtering is enough.

pyramid filtering is enabled by default in bitmap settings. it helps a little. i mean even with very high blur value (4, visually very blurry (defualt is 1)) there are a lot of areas with more than 1 sample per pixel.
per pixel contrast is 0,051 for every channel (default values)

on a next week i hope i'll find time to make a simple scene to demonstrate it. too busy right now with other project.

[bart]

I don't understand. If you think it is too blurry visually, then I believe you do want more than 1 sample per pixel.

For example, limit your sampling max to 1 sample per pixel and look at the results. In addition, ...

Try processing your texture ahead of time, resizing it in lower resolutions. Then put a couple of copies of your object with those different size maps in a test scene.

Also, I'm not sure if the 3ds max bitmap pyramid filtering is the same thing, as I'm thinking about. I seem to recall some sort of unexpected behavior from it. I thought there once was a way to be able to read exr and map format files in 3ds max, both able to support pre-constructed pyramid (mipmap) levels. Has that changed?

[Zxx]

For example, limit your sampling max to 1 sample per pixel and look at the results.

quotation from my first post: "when i set max sampling to 1 it renders very fast and texture looks good"

i don't see support for .map format in 3dsmax bitmap map. but it supports openexr.
also, about filtering (from 3dsmax reference):

Use mental ray Map Manager
When on, maps (typically file-based bitmap images) used in materials and shaders are read from disk and if necessary, translated to a format that the mental ray renderer can read. When off, maps are accessed directly from memory, and translation is unnecessary. Default=off.

Following is a complete list of differences between turning this option on and off:

When on:

- mental ray reads textures directly from disk (mental ray is able to flush textures out of memory when memory is low). Also, textures are loaded only if needed.
- mental ray uses its built-in pyramid filtering system. These pyramid lookup tables can be flushed out of memory when memory is low.
- Texture formats not supported directly by mental ray are read by 3ds Max and sent, before rendering begins, as binary data to mental ray.

When off:

- 3ds Max reads the textures from disk, and then sends individual pixel colors to mental ray as they are needed.
- Note3ds Max reads the textures from disk and keeps them stored in memory between renders. This can make renders faster, because the bitmaps don’t need to be reloaded every time. 3ds Max will not read the texture from disk if it was already loaded previously (for example, in a previous render, for a Material Editor preview, or for displaying the map in a viewport).
Rendering uses a pyramid filter shader that is identical to the standard 3ds Max pyramid filter system.

Turning this option on is useful for large scenes that take a lot of memory to render. Turning it off is quicker, because textures already loaded in memory don’t have to be reloaded by mental ray.
NoteTurning the option on and off might result in very small differences between rendered images because of the different algorithms used in the mental ray map manager and the 3ds Max map manager.

[strangerman]

You'll have to unhide the texture_lookup2 shader to be able to load .map files into max, but it has its drawbacks, like the lack of tile control and so on. The best thing to do if you plan to use .map files is bake all textures to a propperly unwrapped uvw map channel in order to avoid the use of tiling features.

[ldinc]

Well crap, it appears Max doesn't expose the per-object sample settings like Maya does. I just looked in 2013.

In that case filtering the texture is best.

Hey... I had the same problem...I had a scene where it was 1064 polys and 8 2K textures for an residential intersection...where I had grass textures.


First, I just like to say that Maya guys should not be responding to these Questions. I talked to a Maya MR guy and when I had the
told him the problem...right away he said to convert my textures to .map files...NO SUCH THING IN Max...never heard of it.

I have an AMD machine with 32 cores and my simple scene took 51 sec. Because I felt it was a filtering issue I decided to Check ON "Use mental ray Map Manager" and my render time went to 11 sec ...Try this...I tested multiple machines and multiple scenes and in every case where this was checked on I got better render times. Why this is not on by default I have no idea!

[Byteman]

right away he said to convert my textures to .map files...NO SUCH THING IN Max...never heard of it.

I have an AMD machine with 32 cores and my simple scene took 51 sec. Because I felt it was a filtering issue I decided to Check ON "Use mental ray Map Manager" and my render time went to 11 sec ...Try this...I tested multiple machines and multiple scenes and in every case where this was checked on I got better render times. Why this is not on by default I have no idea!

That map conversion may be a good thing. I ve also seen that message and I remember that Imfcopy command, if I remember name correctly, in one of max's mental ray folders. I never could have time to check the usability of that command. Don't know if it helps but it may be a useful thing. Mental ray doesn't like some texture formats arbitrarily.

One more thing: I remember mental ray map manager causing dark seamlines at the tiling edges of textures on my several scenes when I use distributed bucket rendering. I couldn't find a reason but lucky I noticed it. It prevented me from using DBR for some time.

Best regards

[strangerman]

Hey... I had the same problem...I had a scene where it was 1064 polys and 8 2K textures for an residential intersection...where I had grass textures.


First, I just like to say that Maya guys should not be responding to these Questions. I talked to a Maya MR guy and when I had the
told him the problem...right away he said to convert my textures to .map files...NO SUCH THING IN Max...never heard of it.

I have an AMD machine with 32 cores and my simple scene took 51 sec. Because I felt it was a filtering issue I decided to Check ON "Use mental ray Map Manager" and my render time went to 11 sec ...Try this...I tested multiple machines and multiple scenes and in every case where this was checked on I got better render times. Why this is not on by default I have no idea!

I'm giving you the solution to load .map files into max right HERE, the very prior comment to yours, and kzin is kindly giving you the solution to convert bitmaps to .map files HERE.

texture_lookup2 shader is hidden by default in one of the includes inside the mental ray folder located in the 3dsmax installation folder (/3ds Max 2013/NVIDIA/shaders_standard/mentalray/include/base_max.mi, somewhere near line 298, just put a # before the word "hidden" to show it in max GUI), and imf_copy.exe is in /3ds Max 2013/NVIDIA/. there is a script written by Dave from Maxplugins.de which helps you to convert all your scene maps to .map or you can do it by hand following kzin's instructions.

[Remydrh]

First, I just like to say that Maya guys should not be responding to these Questions. I talked to a Maya MR guy and when I had the
told him the problem...right away he said to convert my textures to .map files...NO SUCH THING IN Max...never heard of it.

Regardless of exposure, sometimes you can still get to the correct controls if you know what to look for.

You might also want to try tiled/mipmapped EXRs instead of .map. See if that works inside the file node. They are converted in a similar way. This should take advantage of mipmapping as well.

Textures will cause render time changes more often and more extreme than the raytracer so it's probably best to have a good texture pipeline. If 3ds Max will make use of a rayrc you can specify the texture caching type and amount from there. We found this can dramatically reduce render times when used correctly on scenes with lots of textures.

[Zxx]

well, here is the illustration
1. the clean render without texture:
sampling 1-16, time: 2:16
1test.jpg
diagnostic
1diag.jpg
clean and fast.


2. added simple texture to diffuse slot (filtering = pyramid, blur = 1):
sampling 1-16, time: 13:31
2test.jpg
diagnostic
2diag.jpg
render time dropped considerably.

3. used fixed sample rate 1 sample per pixel:
sampling 1-1, time: 1:49
3test.jpg
again, clean, fast and sharp. texture looks totally acceptable, only teapot edges requires more samples