<< Back to Tutorials
Rendering out into elements is a fantastic way of having more control over your images and animations in post production. There are however few tutorials that show how to do this from start to finish in an efficient way. This tutorial will guide you through the entire process from start to finish of rendering a scene into various passes, and how to composite it back together in Photoshop. This can also be applied to After Effects or any other compositing program if you are creating an animation.
.
In this tutorial we will:
- Set up the scene in 3ds Max to render out various elements.
- Composite them back together using photoshop.
- Add specular bloom to bright areas to enhance realism.
V-Ray is a full HDRI renderer producing full high dynamic range images. This is great for post production as it allows you to change the image exposure without losing any quality. In order to take advantage of this we need to set up V-Ray to save floating point files.
.
So whats OpenEXR and HDRI?
Both OpenEXR and HDRI images are high dynamic range files capable of holding much more colour information than a monitor can display. A normal 8-bit per channel jpeg or tiff contains a total of 16.7 million colours (256*256*256). A high dynamic range file is capable of holding 32-bits per channel, allowing it to contain a total of 4722366482869645213696 different colours! An OpenEXR file is practically the same as an HDRI file, but it can contain many layers and compression methods. It was developed by ILM for use in-house for their renders, and has been made freely available to all 3D users.
So why is this useful?
The amount of colour information stored in a full 32-bit floating point file allows you an incredible amount of control in post production. For example, below is a render of a sphere with a vray light material applied with an intensity of 100. To the left is a normal 8-bit per channel bitmap, and to the right is a 32-bits per channel float. Notice as I reduce the exposure what happens. On the normal image the sphere simply becomes darker. However on the right the extra light information in the exr file is telling photoshop that the light is still very bright and it was actually a red light but was so bright it appeared white. The normal 8-bit per channel image has lost a large amount of colour information when it was saved, however the high dynamic range image has retained all the information.
.
Hopefully this example has shown you why rendering in hdr is so powerful. HDR Files retain a massive amount of colour information including totally burnt out areas that appear white. The only slight issue with rendering to hdri is the jagged edges produced due to the massive contrast in colour levels (Anti-aliasing filters have a hard time blending between the two huge differences in contrast). There are a few workarounds to this such as:
- Adding Specular Bloom (which we will be doing later in Photoshop)
- Rending at a higher resolution, and then downscaling the image. This is actually done very regularly in CG as it gives renders that extra clarity and definition.
- Use a non-sharpening anti-aliasing filter such as the Lanczos filter, rather than Catmul-Rom or Mitchell.
- Make V-Ray work as a normal 8-bit per channel renderer by clamping the output values. Under Color Mapping tick Clamp Output and Sub-Pixel Mapping. This is a very bad solution though as it forces V-Ray to render an 8-bits per channel image.
The workaround to this is to add specular bloom which we will be doing later.
.
Setting up the Scene
Firstly, we need to set up 3ds Max. If you do not have a scene to work on, please download the 3ds Max file below.
With V-Ray its possible to save all render elements into a single OpenEXR File, allowing you to open one file in photoshop with all the render elements as a separate layer.
Turn on V-Ray Frame Buffer and tick Render to V-Ray RAW Image File. Click Browse and choose a location to save the image. Once you have chosen a save location change the file extension from .vrimg to .exr and press save. V-Ray will save out a 32-bit floating point exr ready for us to use in Photoshop.
Some Useful Information about V-Ray:
By default V-Ray is set to save 16-bit floats rather than 32-bit floats. The exr that is saved from V-Ray is technically a 32-bit file, but the information within it is really 16-bit. This isnt a problem as 16-bit images save disk space while still providing ample headroom for colour corrections in post. It is possible to force V-Ray to render out a true 32-bit float, but this is only accessible through MaxScript. I have written a script that can do this very easily with the click of a button and it can be found on my scripts page. I would note though that 32-bit floats are very rarely needed in post. If you want to change the levels of something to the extent where 16-bit floats are not good enough, perhaps it is your scene that needs correcting, rather than the rendered image.
.
Next its time to set up all the render element passes.
Go to the Render Elements tab and enable Elements Active. Click Add and select these elements:
VRay_Reflection
VRay_GlobalIllumination
VRay_Lighting
VRay_Specular
If you need an alpha channel add VRay_Alpha.
For this exercise these four are the only elements required. There are lots of other passes available, but this exercise will just illustrate the most important ones.
PLEASE NOTE IF THE VRAY FRAME BUFFER IS ENABLED, ELEMENTS WILL APPEAR UNTICKED AND TURNED OFF. THIS IS NORMAL AND WILL RENDER FINE.
Finally, once everything is ready press render.
.
Compositing the Elements in Photoshop
Open up the rendered OpenEXR file in Photoshop. If you do not have the file but would like to learn how to composite the passes please download the file below.
If you can only see one layer in Photoshop called RGBA its because you need a plugin called ProEXR to read the rest of the layers. There is a free 15 day trial for this plugin if you would like to use it which can be found here. Adobe Photoshop can read exr files but in a very limited way, which is why this plugin is required.
An alternative to using this plugin is to render out each frame into a seperate exr file. Simply turn off the V-Ray frame buffer, enable all the render elements and choose a save location.
Once the plugin is loaded correctly you should be able to see all these passes. The top layer RGBA is a pre-calculated composite of all the elements. It isnt needed so you can hide it from view by pressing the eye to the left of it. The Specular layer is actually not needed in this example scene so can be safely deleted. I added it to show you that it is an important element if you have any specular reflections in your scene.
.
We are going to composite all the layers together by changing the blending mode. At the moment they are all on normal.
As you can see some of the blending modes are greyed out. This is because the image is a full 32-bit per channel file. If for any reason you want to use a greyed out blending mode you will have to change the file to either 8 or 16-bit perchannel. This can be done by pressing Image>Mode>X_Bits Per Channel.
We want to add all of the elements together, so change all of the layers to Linear Dodge (Add). It doesnt matter what order your layers are in as they are all being added to each other.
Your image should now look like the reference RGBA layer unhide it to check.
Simple huh!
.
Adding Specular Bloom
Specular bloom really helps make an image go from being good to great. Its also a really handy way of getting rid of aliased (jagged) edges around very bright lights/reflections.
Jagged edges are a problem with all HDRI renderers and not just a problem with V-Ray. Very bright areas can be much more intense than other areas in the scene, and for this reason even on very high quality render settings jagged edges can occur. A simple solution to this is to add specular bloom to the very bright areas in order to blur the jagged edges into the rest of the scene. This is a very good solution as it allows you to have full 32-bit HDRI images and it also acts the way a normal camera would in real life.
In Photoshop duplicate the VRay_Reflections layer and hide all layers except the newly duplicated one.
Adjust the Gamma by pressing Image>Adjustments>Exposure and use the Settings in the Image. Change the opacity of the Layer to around 3%. This value is very low as the whites are so bright due to the HDRI file. Unhide all the layers and then add a blur to the gamma adjusted reflection Layer by going to Filter>Blur>Gaussian Blur. Adjust the blur amount to around 7 pixels.
.
Sometimes this may not produce the desired results for bloom due to the diverse amount of brightness contained in an hdr file (some whites will bloom massively compared to others). This is entirely accurate and the way a real life camera would behave, but this sometimes may not work for your particular scene. To overcome this you can convert the duplicated layer to 8-bit and then apply the bloom by adjusting the brightness/contrast values. The best way to do this would be to copy the layer into a new image in photoshop, convert it to 8-bpc, adjust the brightness/contrast, and then drag the image back into the main composition changing the blending mode to dodge (add) and adding a blur.
Hopefully you have managed to follow all the steps and create a composited image.
.
So why did we just do that?
Rendering out into different elements, especially hdr elements, allows us an incredible amount of post production control.
For example say we want to change the amount of reflection after the image has rendered. Go to Image>Adjustments>Levels and change the amount of reflection using the levels tool. This is a very simple example of how powerful render passes can be.
.
Thank you for reading this, and I hope you will find it useful. Tim.
V-Ray Render Elements Rendering and Compositing in ...
With V-Ray its possible to save all render elements into a single OpenEXR File, allowing you to open one file in photoshop with all the render elements as a
Render Elements & Compositing - V-Ray 3.0 for 3ds Max
Render Elements & Compositing. V-Ray 3.0 can output deep and multi-part images using the industry standard OpenEXR 2 Optimized Shading and Rendering of Hair
Tutorial: Advanced VRay render elements compositing in ...
Advanced VRay render elements compositing in After Is it possible to retrieve data through glass when rendering. Specifically render elements such as an RGB
Compositing Vray Render Elements - 3D Rendering ...
In the following tutorial we will go through the process of rendering an image in separate passes using render elements and compose them afterwards in photoshop.
V-Ray Render Elements - Rendering and Compositing in ...
Go to the Render Elements tab and enable "Elements Active". Click "Add" and select these elements: VRay_Reflection VRay_GlobalIllumination
// Compositing V-Ray Render Elements // - // 3DTotal.com ...
effectively composite V-Ray render elements 'Compositing V-Ray Render Elements' the sRGB button in the V-Ray frame buffer during or after rendering
Vision: Compositing Vray render elements
Specialize in Lighting, Rendering, Compositing, and Modeling-Texturing. And recently working as Lead lighting Artist.
V-Ray Render Elements - Rendering and Compositing in Photoshop
HOME ABOUT CLIENTS SHOWREEL VISUALS CONTACT TUTORIALS V-Ray Render Elements - Rendering and Compositing in Photoshop Rendering out into elements is a fantastic way of
Compositing V-ray Render Layers in Photoshop
3D, Adobe Photoshop, Compositing, not a lighting/rendering tutorial, we first have to enable them in the V-ray Render Elements tab within the Render
Improved V-Ray RT - V-Ray 3.0 for Maya
hair and fur and volume rendering. Render Elements. V-Ray RT GPU supports a number of additional shading nodes and Render Elements for compositing. VRay Proxy
Travelling is my life
ConversionConversion EmoticonEmoticon