Vray for Sketchup, a program that requires a lot of time to learn. To fully understand Vray would be very difficult to explain in one article so I will not be doing that. Instead, in this tutorial, I will be posting up screenshots of the settings that I use (from lots and lots of trial and error, experience, questions and answers). I will try to explain some of the common variables also. As well as this, I will post up links to other reference websites for Vray. This tutorial will not discuss materials and how materials are made, only Vray option settings.
Please first understand that Vray is not a magic weapon that allows you to instantly create fantastic images. Far from it in fact. It is only one of the tools in your toolbox. For me, Photoshop is probably the ultimate tool, but that's only personally. To me, I relate using Sketchup, Vray and Photoshop to building a real model. Sketchup is the mould, and Vray creates the model formed from the mould. Photoshop is used to refine, and add the ultimate details to the model.
Also, having a knowledge of photo composition is ideal. Understanding perspectives and how a good photograph is composited is critical. Analysing striking photos, reading photography magazines and books, will definitely help you understand what makes a good image.
I am using the latest version of Vray so the settings and names of settings will differ if you are using an older version, but it should be very similar. The images below are what have been created using these settings.
In these images above, the water material was very fiddly to play around with. In other tutorials, I will have demonstrations with materials. Bear in mind that these settings are quite high and take a while to render. I will highlight some points which you can change to decrease the quality and render time for test renders.
First thing... where is the options tab? On the toolbar, after installing Vray:
Only thing I touch here is override materials. This does what it says... when you render, it will override every material to the Override Material Color.
Use Adaptive DMC as your image sampler. On previous versions of Vray, this may be known as, I believe, QMC. The anti-aliasing filter softens edges producing better edge results. I always have this on. Different filters produce different effects. For architectural renders, often it is good to use the Catmull-Rom filter as it produces sharper results. However, it can sometimes produce a moire effect. The Color Threshold value can be reduced to say 0.1 for faster test results.
Quite a difficult feature to use. It creates the shimmering results seen in the render above. Caustics also create the light effects you see when you shine a light through a diamond, for a example. It takes up a lot of render time and is not always necessary. Usually, I turn this feature off.
Only setting I use here is the DR setting, which means distributed rendering. This allows multiple PCs to be used for one render, sharing the power of the PCs. You need to input the IP address of each computer in there, as well as having the program DRSpawner on each of the PCs (which comes with Vray).
Unless you have materials with displacement, this setting need not be changed. 1000 subdivs provide decent results.
GI Color controls the lighting that affects the image. BG Color does not affect the lighting but only creates the background of the image. Unless it's something special, I keep the texture of each as Sun/sky.
This is where you're photography skills can pay off. I always use the Physical Camera which essentially acts like a real camera, where you can change the shutter speed, ISO, F number, etc.
These are additional channels that will also be rendered should you wish to. As a default, RGB color and Alpha are required. Some of the others can prove to be quite useful when using in post production. I haven't used many of them, but one that I have used is Render ID, which differentiates materials by colour.
Here, you can change the final output size. You can also choose to render directly to file or render to something called a VRImage. This is useful should you wish to render a alrge file and you are running low on memory. However, you will need an extra program found on the ASGVIS website, to convert the file to OpenEXR.
GI (Global Illumination) - always on.
Ambient Occlusion is a new feature in the latest version of Vray. Very useful tool that helps create wonderfully realistic results.
The Primary Engine, I always use Irradiance Map and Light Cache. DMC/QMC really eats up time, so I would not use that... plus it doesn't give great results.
The Min Rate and Max rate can determine the quality of the render. Play around with it to see the different results. Always keep the min rate at a negative value. The HSph. Subdivs also control the quality. 50 is quite decent, but for higher quality renders, a value of 100 can be much better. However, this does greatly increase the render time.
The default value of 1000 subdivs produces rather good results. I never go beyond it. However, for test renders, I lower that value way down to the values of 100 or so.
The default Adaptive Amount value is 1 on previous versions of Vray. Make sure that this value is changed to 0.85. Just do it! The noise threshold value here is 0.01. This produces quite good results and a sharp image. You can reduce this value to say 0.1 for quick tests.
Play around with the Color Mapping type to test the results.
http://forum.asgvis.com/ - this website is the home of Vray for Sketchup. Many professional users reside here and can answer many of your questions.
http://www.spot3d.com/vray/help/150SP1/index.htm - a very useful website. The tutorials and information is actually for Vray for 3DS Max, but there are a lot of similarities between the programs and you can learn a lot there.
I hope this somewhat comprehensive tutorial will help you in some way or another.