iray 5: iray in standalone mental ray

So far, I told about exporting an mi file. Now here is the shader conversion for iray.

iray supports mia_material. To reuse current scenes, it is nice if I could convert the 3dsmax shaders to mia_material (Arch&Design) shader. I could imagine that some of other shaders will be supported also, but, iray is a CUDA program. CUDA has a divergence problem, it means, if many kind of shaders are in the scene, the performance becomes low. That's natural. A shader is a function and many different shaders are running on a CUDA device, I could see it will be slow. But, if the same function everywhere, then CUDA works well. (in theory. If function itself has a lot of branches, then there is a problem. Though many obstacles are there, but many kind of shaders seems to have not so chance. ) Also I imagine there is less trouble if I use the mental images native supported shaders since iray is a new renderer. In my personal opinion, I would convert the shaders.

You can find 3dsmax shaders to mia_material convert 3dsmax script here (https://code.google.com/p/shitohichi-tools/source/browse/#hg/mentalray/max2mia_material). This is based on Zap's VRay shader to mia_material converter (http://mentalraytips.blogspot.com/). Thank you, Zap. You can find two scripts. The main script is yh_max2mia_material.ms. Open this and evaluate, then the shaders in the scene will be converted. (yh_material_object_map.ms is a collection of subroutines. Therefore, this script is also needed.)

Of course, automatic conversion never be perfect. Some will fail. But, I think this is a good start point if there are many shaders in your scene.

From next week, SIGGRAPH starts. (I've never been SIGGRAPH.) I assume there is some iray demo there.

I concludes the shader conversion story here, at least this moment.

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iray 2: iray in standalone mental ray

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iray 3: iray in standalone mental ray

How to export mi file from 3dsmax. 1. Assign mental ray renderer as Production renderer First open the Render Set Up dialog. Figure export_mi_1 show that opening the rollout of assign renderer and then choosing the mental ray renderer as Production renderer. Figure export_mi_1 2. Export a mi file from 3dmax. Choose Render Set Up --- Processing Tab. First you need to choose a filename as in Figure export_mi_2. Without a file name, the checkbox of 'Export on Render' is disabled. This was difficult for me. I wanted to export a file, but Export on Render is disabled. I wish I could choose the Export on Render and then see a warning message, ''an export file name is not specified.'' Next, push the Render button, then a mi file is exported. Figure export_mi_2 This is also difficult for me. When you ' export ' a file, push the ' render ' button. I wish it was like When you ' export ' a file, push the ' export ' ...

A note of mental ray/iray camera terminology.

The original mental ray camera is a pinhole camera. Therefore, some of the terminology differs with a normal camera. I will write them down here. aperture: This is the film width size. This has no relationship with lens aperture/opening. mental ray's camera was a pinhole camera, there is no lens aperture. focal: This is the distance from lens to the film (sensor). Pinhole camera always focused, so there is no focal length meaning. But using parameters aperture and focal length, we can compute the horizontal field of view. I think these two parameters exist for this purpose. aspect ratio: This is film(sensor)'s aspect ratio. There is no relationship with pixel resolution and camera geometry. aspect ratio = film width/film height. Note: If we use aperture, focal, and aspect ratio, we can compute the vertical field of view. mental ray/iray camera model (pinhole camera) without lens shader Current mental ray/iray can have depth of field effect, etc., this termino...

taming mental ray (English version)

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