درس رائع لتحسين إعدادات الرندر والإضاءة بالفيراي

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Search Keywords:
interior, lighting an interior

Note: The scene for this tutorial is provided by Wouter
Wynen from Aversis (http://www.aversis.be/).
For further discussion of this topic, see
this topic on the
VRay forum.
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Step 1. First render
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1.1. Open the scene (which can be found
here).
1.2. Assign VRay as the current renderer.
Since the default VRay settings are not very well suited for a fast
initial preview, we'll make a few quick adjustments before the first
render.
1.3. Check the Override mtl option in
the Global switches rollout, click the
button next to it and select a default VRayMtl material.
1.4. Set the Image sampler type to
Fixed.
1.5. Set the resolution to 400 x 325.
1.6. Set the Region size in the
System rollout to 32 x 32 pixels.
1.7. Optionally, you can turn on the Frame stamp to print the render
time on the image.
1.8. Render the scene:

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Step 2. GI preview
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2.1. Turn GI on from the Indirect illumination
rollout.
2.2. Select Light map as both the primary
and secondary GI engine.
2.3. In the Light cache rollout, set the
Subdivs to 500,
since we want only a fast preview. We'll return this to 1000 for the
final rendering.
2.4. Set the Interp. samples of the
light map to 5 for a faster rendering.
2.4. Turn on the Show calc phase
option for the light map.
2.5. Render:

The result is quite noisy, but it does give a good idea of what the
scene lighting is like.
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Step 3: Tweaks
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3.1. Since the scene looks too dark, we would like to brighten it a
bit. There are several ways to do this. One is to increase the power of
the lights. However, this will make the directly lit areas of the image,
like the patch of sunlight, too bright while indirectly lit regions will
remain relatively dark. Here is an example of this (all lights are x 2):

You can see that the increased light power has made the image
brighter, and also has increased the contrast of the lighting. The scene
still looks dark though. We can increase the light power even further,
but this will blow out the directly lit areas too much, and will slow
down the GI calculations later on. So, instead of increasing light
power, we will simply make the material brighter.
3.2. Go to the Material Edtior and put the default VRayMtl in one of
the slots (it shows up as being used in the "Environment" in the
Material/Maps browser).
3.3. Make the diffuse color of the material RGB (200,200,200).
3.4. Render

The result is much better. We still have the same amount of light
entering the scene, but it is bounced around more and thus increases the
overall brightness of the scene.
At this point, you can adjust the ratio, color etc of the lights,
while getting a relatively fast feedback on the lighting.
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Step 4. Better GI.
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The GI settings that we used are good mostly for fast previews, while
you are still adjusting the scene. Once you have settled on the
parameters of the lights, it's time to refine the GI solution.
4.1. Set the primary GI engine to
Irradiance map.
4.2. Select a Medium preset for the
irradiance map.
4.3. Turn the Show calc phase option
for the irradiance map on.
4.4. Render the scene.
Rendering takes more time now as VRay needs to calculate a more
precise GI solution.

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Step 5: Better antialiasing and less noise
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The GI looks ok now, but we still have no antialiasing and there is
noise from the area light at the window. We'll deal with those now.
5.1. Set the Image sampler type to
Adaptive QMC.
5.2. Turn GI off.
5.3. Render

We do have antialiasing now, but the noise is even worse. We'll
adjust the QMC sampler to improve that.
5.4. Set the Min. samples of the QMC
sampler to 16 and the
Noise threshold to 0.002.
5.5. Render.

The noise is less, but there is still some of it. Reducing the
Noise threshold and increasing the
Min. samples any more will not help. We
simply need more samples for the area light. One way to do that is to go
to the parameters of the VRayLight and increase the subdivs. However, if
you have many lights in the scene, this is quite a lot of clicking.
Instead, we will use the Global subdivs
multiplier to do that.
5.6. Set the Global subdivs multiplier
to 4.0 and render:

There is still some noise, but we can continue to increase the
Global subdivs multiplier until the
result is good enough; 16.0 seems to be a
good value.
5.7. Set the Global subdivs multiplier
to 16.0 and render:

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Step 6. Final rendering with GI
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The increased Global subdivs multiplier
affects the irradiance map too, so if we render now with GI, it will be
too slow. We'll need to do some adjustments.
6.1. Turn GI on.
6.2. Set the Hemispheric subdivs for
the irradiance map to 8.0 to compensate for
the increased Global subdivs multiplier.

6.3. Render

This completes the first part of the tutorial. In the next part,
we'll add the scene materials.
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Step 1. Rendering with materials
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1.1. Turn the Override mtl option in
the Global switches rollout
off.
1.2. Turn on the reflection/refraction Max
depth limit in the same rollout.
1.3. Turn GI off.
1.4. Set the Noise treshold of the QMC
sampler to 0.005 for faster previews.
1.5. Render.

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Step 2. Preview materials with GI on
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2.1. Turn GI on.
2.2. For faster previews set the primary engine to
Light cache .
2.3. Render

At this point you can adjust your scene materials while getting fast
previews of how the will look in the scene.
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Step 3. Better GI with the materials
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3.1. Set the primary engine to Irradiance map.
3.2. Set the QMC Noise threshold to
0.002.
3.3. Set the light cache Subdivs to
1000.
3.4. Set the light cache Sample size
to 0.03 (this will make the light cache a
little smoother and slightly faster).
3.4. Render.

This is the final image that we will render at full res in the next
part.
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We now have to render the final image.
Step 1. Adjusting VRay for larger resolution
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1.1. Set the resolution to 1600 x 1300.
1.2. Set the render region size to 64 x 64.
We will need to adjust the irradiance map parameters: since we
increased the resolution twice, we can decrease the irradiance map Min
and Max rate by 2.
1.3. Set the irradiance map preset to
Custom.
1.4. Set irradiance map min rate to -5.
1.5. Set irradiance map max rate to -3.
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Step 2. Rendering the final image.
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2.1. Set the 3dsmax to save the rendered image. For increased
precision, you can choose a 16-bit image format (for example, a 16-bit .png).
Optionally, you can save to a .hdr image; in that case you need to
select the Unclamped color channel in the
VRay GBuffer rollout.
2.2. Press the Render button.
2.3. Go out for lunch.
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The final scene for this rendering can be found
here.
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The image looks ok, but in most cases you will want it to be a little
darker or a little brighter etc. Instead of changing the lights and
re-rendering, you can do those adjustments in an image processing program.
For example, here is the same image with the gamma value adjusted. I used
a .png file and IrfanView for this
purpose, but you can use any other software that you feel comfortable with -
for example,
HDRShop
for .hdr files.

To add a more photographic feel to your image, you can apply some radial
darkening of the corners, for example like this:


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