Wouter Tutorials Standard Studio Lighting

STANDARD STUDIO LIGHTINGauthor:

Wouter Wynen

brought to you by:

©2006 VisMasters. All rights reserved. VisMasters and the VisMasters logo are trademarks of ArchVision, Inc.

All other trademarks belong to their respective owners.

Standard Studio Lightingby:

Wouter Wynen

April 2006

Standard Studio Lighting

This tutorial assumes you have already completed the previ-ous tutorials in the tutorial list.

It will provide a general workflow for a standard studio light-ing setup: create the environment, place lights, adjust render settings.

The V-Ray version I used for this tutorial is 1.47.03.

INTRODUCTION

5


1. Build a test scene lighting tutorial

Start up max and set V-Ray as the renderer.

Go to ‘customize - units setup’ and set both the display unit scale and system unit scale to metric: millimeters.

Create 3 geospheres with radius 35mm and position them like I did.

2. The ground planeWe will try to build an infinite background in a simple way. Usually pho-tographers use a big white or black cloth be-hind their scene, curved at the bottom, so that you will not see a sharp edge be-tween back wall and floor.

There are of course lots of ways to do this. I will start from a cylinder, bend it locally and round it off with a MeshSmooth modifier. This way, your

ground plane is very smooth and round in all directions, making sure you will not have disturbing re-flections from it (like you would when using a box for ex-ample as ground plane).

Click the image on the right to see all settings of the cylin-der, bend and MeshSmooth modifier.

6


3. Create a camera

Now create a camera and position it like in the image on the right. Give it a 50mm lens. Set the perspective viewport to use this camera, enable ‘show safe frame’ so you can clearly see what part of the scene will be rendered.

7


We need three materials: almost white, chrome and red reflective.

Click on the image to see what set-tings I used for the chrome and red material (this should look familiar if you completed the V-Ray basic materials tuto-rial).

Assign the materi-als to the spheres. The ground plane also uses the almost white material.

4. Create materials

5. Test render settingsOpen the render settings dialog and do the following:- set V-Ray as the renderer if you haven’t done so- output size to 480x360px- global switches: turn off default lights- image sampler to adaptive QMC- antialiasing filter “mitchell-netravali”- indirect illumination ON- Secondary bounces multiplier to 0.8- Irradiance map settings: - “low” preset - HSph subdivs = 20- environment: - skylight pure white color, 1.0 multiplier - reflection/refraction pure black, 1.0 multiplier- system: - render region division 50x50px - frame stamp: delete all except render time part.

Render the scene, it should look similar to my image.

8


Instead of the skylight, we will use big rect-angular V-ray lights to light the scene. They will also be useful for creating nice reflec-tions (like we did in page 2 of the material settings tutorial).

Create two V-ray lights and position them more or less like I did.

The left light is 400x350 mm with a 3.5 multiplier and the one on the right 360x500mm with 5.5 multiplier.

Then go to the V-Ray environment rollout and change the skylight multiplier to 0.1.

6. Reflection planes / lights

7. Render what we have for now

I made the right light brighter on purpose, that way you create shadows falling in one direction. If you would set them at equal strengths, the image will be uninteresting as lighting will be a bit flat, coming in equal strength from all directions. The bigger the difference between the two lights, the more dramatic lighting will be.

The first pic shows left=3.5 and right=5.5

The second one has left=2 and right=7

We will continue with the 2/7 settings.

9


8. Noise!

You’re probably wondering why the images are so noisy and take pretty long to render. This is because V-Ray area lights produce raytraced area shadows, and these are very processor intensive. The noise is coming from the low sub-div value in the lights properties.

Because we are using adaptive QMC AA, it is necessary to use high subdivs values for the area lights to get rid of the noise. Try 30 subdivs for both lights and ren-der again. You can see the result in image 1 (click to enlarge).

Now go to the anti aliasing set-tings and change to adaptive subdivision AA with min/max=0/2. With this anti aliasing sampler, you can use lower subdivs than with adaptive QMC to have a similar noise quality. So change the lights subdivs both to 10 and render again. This is image 2 (click to enlarge).

10


At first sight, you might think the adaptive subdivision image is bet-ter (less noisy). But if you look closely, the noise is just different, not ‘better’. In the shadow area you get a ‘blotchy’ kind of noise, compared to the QMC example which is sharp constant noise.

The top image is the adaptive subdivision AA, the bottom one is the adaptive QMC AA.

9. Subdivision vs QMC

11


10. Reduce the noiseWe will now try to reduce the noise for both image samplers to see which one is the fastest for high quality images.

Set image sampler to adaptive subdivision AA, min/max=0/2Adjust subdivs for both lights to 30 and render.The image is noise free. If you zoom in a lot, you can see a tiny bit of the blotchiness.

Now change to adaptive QMC AA, min/max=1/4Adjust lights subdivs to 36.In the QMC sampler rollout, change the noise threshold to 0.002. The adaptive QMC AA is very sensitive to the QMC sampler settings. The noise threshold is the most important one. (QMC sampler controls the quality of all ‘quasi monte carlo’ related calculations. In short, all subdivs settings are qmc related, except for lightcache subdivs)If you zoom in here, you can also see a bit of noise, but sharper and smoother than the blotchiness of adapt subdiv AA.

But in this case, adaptive subdiv AA wins from adapt QMC AA. When you will add more complex materials like glossy ones, and more area lights, fine textures, displacement maps etc, render times for adaptive QMC will not rise as fast as ren-der times with adaptive subdiv AA. Usually when you have lots of glossy effects (also DOF, motion blur...) it is better to use adaptive QMC AA..

12


11. Store with irradiance map

Like I said, the reason for the noise are the raytraced area shadows. Especially for test rendering, we can easily disable them.

The light coming from a V-Ray light (or also from standard Max lights) is called ‘direct’ light. This means it is not GI light (first or secondary bounce). Once this direct light hits a surface, it bounces back a bit (depending on how dark and reflective that surface is). That bounce is called the ‘first’ bounce, and it is calculated by the irradiance map (because we have set first bounce GI engine to irradiance map).

But the V-Ray light has an option ‘store with irradiance map’. This option actually means ‘treat direct light as first bounce GI light’. Instead of casting direct light, the V-Ray light will now cast first bounce GI light and thus it will be cal-culated by the irradiance map. This also means that when it hits a surface, and bounces back, it will become secondary GI light, and it will be calculated by the secondary GI engine, QMC GI in this case.

So by setting the V-Ray light to ‘store with IR map’, the result will be that there is no direct light anymore, only GI light. This means that all shadows will also be created by the GI light. The consequence of this is, that shadow quality doesn’t depend on the V-Ray light

subdivs anymore, but the it is controlled by the GI settings, namely the irradiance map (and QMC GI for secondary bounc-es). This is important, the V-Ray light subdivs do absolutely nothing if ‘store with IR map’ is checked!

(Note that this option only works if IR map is set as first bounce GI engine. If you have for example QMC GI for first and second bounce, and lights with the ‘store with IR map’ turned on, these lights will not cast any light!)

To illustrate the store with IR map option, I rendered two images with the ‘show GI only’ option (global switches rollout). This option renders the image only with the GI light, so with-out any direct light that may be present in the scene.The first one is with normal V-Ray light (without ‘store with IR map’ option). The second one with the ‘store with IR map’ option turned on.

You clearly see that in the first example, with the direct light extracted, there is not that much GI light to be calculated. And in the second example, all light is GI light.

This step is very important, you should really understand the difference between ‘store with IR map’ turned off or on, and the difference between direct/first bounce and secondary bounces.

13


12. Store with irradiance map option (2)

The disadvantage of this option is that there will be more first bounce GI light, but worse, also more secondary bounced GI light (calculating detailed GI light, especially second bounce, is very proces-sor intensive). This means you have to rely on IR map and QMC GI calculations for the creation of nice shadows. In product renders this is not such a big problem, because there will not be much second-ary bounces anyway. Light that hits the top of the spheres for example (first bounce), will bounce back (second bounce) right into the sky. So this second bounce will have no effect on the rendering. Only a bit will bounce in between floor and objects, or from one object to the other. But the secondary bounces will not have such a big influence on lighting and shadow creation.

This will become more of a problem in interior scene lighting. There, the second bounce will not go to the sky, but it will probably hit a ceiling or wall, bouncing again and again... So in these scenes, the secondary bounces do have a great im-pact on final lighting look and shadows. So in this case, it would be a good idea to reduce the amount of GI light, by replacing the first bounce by direct light (‘store with IR map’ turned off). Think about it, instead of relying on first bounce GI light to start with, you now start with direct light which will illuminate a lot of the scene already (quality is perfect, it is direct light), then there is first bounce (IR map) and then second bounce. I will show this in the inte-rior lighting tutorial.

To summarize, for product renders you can greatly benefit from the store with IR map option, as there are not much second-

ary light bounces. You will need to improve the IR map settings, resulting in longer GI calculation, but the actual rendering of the image will be a lot faster, as there are no difficult area shadows to render anymore. The total render time (GI calculation + raytracing the image) will be a lot lower than when you use true raytraced area shadows (here GI calculation will go faster, but actual raytracing will take a lot longer, so combined total result is much longer).

See top image with following settings:- adaptive QMC AA 1/4- noise threshold=0.002 in QMC sampler rollout- IR map: see settings below top imageAs you can see, render times are cut in half, and compared to the raytraced area shadows examples, there is absolutely no noise at all! But shadows are a bit less precise.

Go to the IR map settings and change the min/max to -4/-3 and the HSph subdivs to 20. In the QMC sampler rollout set noise threshold to 0.005 again. These are very fast test render values. Render the image again. Notice how less detailed the shad-ows are now (bottom image, spheres look like they float a bit). But hey, 11.3 seconds is not bad for a fully antialiased image :-)

14

13. The end

This concludes the studio setup tuto-rial.

By now, you should better understand the difference between adaptive subdi-vision AA and adaptive QMC AA, the effect of the ‘store with IR map’ option, and how to create a simple efficient studio lighting setup.

Save this scene so you can reuse it in some of the other tutorials still to come.

Standard Studio Lighting 15

About the author

Wouter Wynen has studied product development for 5 years at the university in Antwerp, Belgium. During these years, his interest in 3D modeling and visualization grew more and more. In the end, it even overpowered the interest in product design.

After graduation, he founded the company Aversis, offer-ing 3D viz & webdesign services.

Standard Studio Lighting 171717

Standard Studio LightingHDR Images in V-Ray

share - learn - inspire™

Wouter Tutorials Standard Studio Lighting

Documents

Transcript of Wouter Tutorials Standard Studio Lighting