Pan down to the "output" rollout and check the "enable color map" function.
Click on the "add point" point button, to add curve points. Tweak and add more points whilst test rendering, to assess the changes. (Fig.19)
Note how the areas of the environment bitmap close to the sun disk have a rim of reddish/yellowish color around its pixels. To help accentuate this effect, go back to the main "mr physical sky" parameters. In the "sun disk appearance" group, increase the disk and glow intensity values to about 25.0.
Next, we are going to test render without the "material override", and set up for the final render.
Disable the "material override" function, in the render setup "processing" rollout.
Enable the FG process and test render. (Fig.20)
The render is looking reasonably ok now. The next stage is to save up the final gather files and send the final high resolution render.
With the FG saved, mental ray will bypass the FG process and concentrate mainly on rendering. This will subsequently reduce the rendering times dramatically. It is highly commended to use one computer only, when executing this task.
Once saved, one can then use multiple computers to reuse the pre-saved FG file to render the image.
Mental ray is very powerful and efficient in enabling users to save the FG file at a small output resolution (i.e. 320x240), and later reuse it for your final high resolution (i.e. 5000x3750), without artifacts.
Note that, the camera view, image and pixel aspect output size need to be locked beforehand.
Moreover, when network rendering, it's vital to have this pre-saved FG file in a location where other computers can "see" it and reuse it.
With the camera view, image and pixel aspect output size locked, we can now begin setting up the final FG parameters.
On "render setup" dialog, under "indirect illumination" rollout, increase the "initial FG point density" value to about 0.7.
This parameter is very useful to add depth to the scene and help correct most lighting artifacts.
The value of 0.7 seemed sufficient for the results desired however; one may tweak these values as desired.
Note that, higher values will result in higher FG processing time. Default 0.1.
Increse the "rays per FG point" to 150. The value of 150 is often the minimum required to achieve a nice and smooth interior lighting however, one may tweak these values as desired.
This parameter helps to improve FG accuracy by shooting rays in the scene. Higher values equate to better results however the FG processing time will increase. Default 30.0.
The "interpolate over num. FG points" is very useful to correct most FG artifacts however; very high values will result in less depth in the scene.
Increase the value to 80.Note that, although very useful and effective, this parameter has little or no impact in the rendering time.
The value of 0 enables the mental ray "brute force" rendering ; which essentially renders the scene without the FG pre process (i.e. raw); this will subsequently increase the rendering times dramatically.
On the "processing" rollout, enable the "geometry caching" function. When enabled, this function caches the scenes geometry every time a render occurs.
For faster render translations; simply lock it to bypass this process. One should only lock it when all geometry changes had been addressed.
To delete any previously cached files, simply click the "clear geometry cached" button, and unlock it.
Default 50.0 (Fig.21a and Fig.21b)
With the above parameters set, it's now time to set mental ray to cache the FG maps.
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