V-Ray is a rendering plugin for lots of 3d software packages that can reproduce very high quality, realistic renders of models featuring lights, materials, atmospheres, etc. It is a powerful program but can be a little tricky to get started with. This is a V-Ray for Rhino run through which covers the basics of setting up and rendering a scene in Rhino.
LAUNCH RHINO AND V-RAY
Rhino has a basic rendering engine built in, to switch to the V-Ray renderer instead and allow access to all of its features you must first choose it as your renderer. Once Rhino has started and you have opened a model then select from the top menu Render -> Current Renderer -> V-Ray for Rhino
This will present a number of V-Ray tool bars – the most important is probably the V-Ray Asset Editor
Inside the V-Ray Asset Editor box is a teapot icon – click this to render a basic image of the currently selected view. This has no special lights so just uses a generic light to illuminate the model and a regular studio background. This render shows in a separate window – the V-Ray Frame Buffer.
Once the render is complete it is possible to save this image by clicking on the Save Current Channel icon and specifying a location for the file.
The Teapot icon with the green play button will start an interactive render – this will keep the render window updating as you make changes. This can be useful to get immediate feedback on lighting types, etc. (though with large files will start to drag).
ADDING LIGHTS AND BACKGROUND
V-Ray has a number of lighting options that can bring the view to life. You can use combinations of lights to have the model illuminated from different areas – but be aware that multiple lights will add to the processing time of the render.
DOME LIGHT
A dome light is a general all-over light that is shines inward to the scene evenly. Click on the top menu: V-Ray -> Lights -> Dome Light then place it anywhere in the scene (does not matter where, it is just a symbol). You will be prompted to use a light texture (a HDRI image) but you can click cancel for now and have just a plain background.
In this model an “infinite plan” has been also added – this is just a ground plan that stretches forever and can be useful to underpin the model. Note how there are soft, subtle shadows around the bottom of this model falling onto the plane. To add the infinite plane select V-Ray -> Objects – Infinite Plane.
Back in the Asset Editor click the light bulb button and select the new Dome Light. This will show the parameters of this new light; you can change parameters of the light -including intensity and colour.
An important parameter here is the Colour / Texture HDR – currently with nothing in it. Clicking to the right of this gives a number of options to give to the dome light which create background / sky effects. One effective option is to use an image – or an HDRI image – to use as the background. This type of image will accurately illuminate the scene with the light features of the image used. HDRI images can be created from photos of your site or there are many of them available online too – a good source is the website HDRI Haven. If you download a suitable image from here it can be used as your light source in the dome.
With the dome light selected in the Asset Editor click on the checkerboard icon next to colour/texture HDR and select bitmap, then browse to where the HDRI image has been downloaded to. The render will now update to reflect the features of the HDRI image.
In this example stark moonlit night background was chosen – note how the shadow is falling away from the model from the direction of the light in the image. It is possible to select the light object in Rhino and rotate it – this will rotate the dome and the direction that the light is falling from.
Another option for dropping into the colour/texture slot is a sunlight. Right click the checkerboard icon and clear the bitmap. Then click again and this time select Sky:
This reveals two circular / semi circular sliders that can be dragged to simulate orientation of the sun in the sky and also its height (time of day). When this is activated it is likely that the render is very over exposed – this sunlight is very bright.
To fix this change the exposure setting of the V-Ray camera:
In the Asset Editor, click the cog icon and look for the Camera properties. The Exposure Value is likely to be set at 10, for the sun to work best this value ought to be something like 13. This exposure value setting is useful for quickly changing the light setting for the whole scene – and all the lights that might be in it.
Once this set then you can hop back to the light properties and change the angles with a more effective result.
This Sky feature also has the option to add computer generated clouds to the sky as well as different sky models that can be worth experimenting with to get particular types of skies.
