Introduction
Sometimes you’ll want to change the background of a rendered image in postwork. Poser can save its renders on transparent background (.png format). Bryce unfortunately can’t. However, it offers the possibility to render Object Masks which can be used in a 2D program such as Photoshop.
In this tutorial I’m going to show you two methods for rendering object masks: the “normal” method and my refined one. I’ll also explain how you can use the object masks in Photoshop.
I am using Bryce 5.5 and Photoshop 7, but it will work with older Bryce versions, too. And the Photoshop procedures may be similar in other 2D applications.
Step 1 - The “normal” method
Here we see one of the plants of the Xfrog-Samplers, rendered the normal way.
I saved the image as a file because I'm going to use it soon.
IMPORTANT for the next steps: The plant must be selected.
Now we set the render mode to 'Object Mask' and start the render.
And here is the result of the rendered mask.
The shape of the leaves seems to have changed.
Let's save this image, too, and check the whole thing in Photoshop.
Step 2 - Working with layer masks in Photoshop
Start Photoshop and open the rendered image.
First, we have to convert the fixed background layer to a normal layer. This is done by double clicking the layer in the layer palette.
Next, we add a layer mask by clicking the symbol (on the bottom of the palette).
Then we switch to the 'Channels' palette. In addition to the four default channels there is now a new one for the mask. Switch on the eye symbol of this channel, otherwise it cannot be edited.
Now we need the rendered mask. Open the second file, select the whole image (Ctrl-A) and copy it (Ctrl-C).
Switch to the first file with the image. The mask channel should still be selected. Here we paste the mask (Ctrl-V). Switch off the eye symbol and look at the result.
It is obvious that there is something wrong. There still is a lot of background around the leaves.
The reason for this is: When rendering object masks, Bryce renders the shape of the 3D mesh. But the leaves of this plant get their shape by the texture with the transparency settings -- which are simply ignored by Bryce.
Therefore we need a trick to render the transparencies, too.
Step 3 - How to render a mask with transparencies
As we said: Transparencies are rendered in Bryce only the normal way and not with the masking mode. This means, we have to render the image the normal way and simulate the black-and-white of the mask.
Switch back to Bryce.
IMPORTANT: First thing we switch the render mode from 'Object Mask' back to normal (just uncheck it).
Hold down the Ctrl-key and click on the leaves of the plant. By this you can select single parts of the group without having to ungroup it.
Click on the small 'M' to open the material editor. Here we change the 'Diffuse' and 'Ambient' colours to pure white: just click in the oval field and choose the colour. Set the intensity for both to 100. If there are any bump settings, switch them off. Only the transparency settings remain unchanged.
Repeat this for every part of the object.
Now we need a black background. There is a good preset in the Sky library.
Open the Sky editor by clicking on the little cloud with the rainbow.
Here we'll switch off the shadows. By this we avoid getting grey hues in our mask.
Then we drag the sun so that it shines on the object directly from the front. This reduces the risk of grey hues even further.
Finally we delete the ground plane.
Step 4 - It works!
Let's render now. We get a perfect mask with all transparencies.
This mask can be used in Photohop as described above. The result is perfect.
Note: When you have very complex objects (like Poser figures) it is a lot of work setting every single part to white. Here it makes sense to use a combination of both masking methods: the tradional mask render for all objects without transparencies, the new method for transparent parts (like hair or clothes with lace). I used this combination to put this dancer onto a new background.
Hint: It may be easier if the old background has a similar hue as the new one because sometimes there remain some pixels of the old colour. In any case, higher resolutions produce better results.
I hope that this tutorial has shown you some new possibilities with Bryce. Just keep experimenting.
Happy rendering,
esha
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