Using the MRGBZGrabber in Zbrush 2 |
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The MRGBZGrabber is Zbrush 2's tool for simultaneously capturing depth and color information from a Zbrush scene and transferring it to other applications.
The MRGBZGrabber captures both a 16-bits-per-pixel grey-scale alpha map and a 8-bits-per-pixel (24-bit) color map. The 16-BPP image can be used as a displacement map
or as a normal map by running it through the nvTools NormalMapFilter in Photoshop. For normal maps, the grey-scale image will need to be converted to an 8-BPP
RGB file.
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Here is a brief work-flow that demonstrates a direct way to use the MRGBZGrabber to transfer depth and color data
from Zbrush 2 to Photoshop.
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1. To use the Grabber on an image, select the grabber from the tools menu - the icon for the grabber is a square
with four arrows pointing out of it similar to a compass (see illustration). |
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2. Once selected, click and drag the grabber across the area you want to sample. The grabber marquis will quickly sample the area
and store the depth information in the alpha menu. The color information will be stored in the texture menu. When sampling the image,
it's important to note the "Shaded RGB" option is ON by default in the MRGBZGrabber's modifier setting. This is significant because if
you sample with this setting on, Zbrush will capture the active lighting in the scene (basically, the color grab is a snapshot of what
you see in the scene if you leave this on). If you turn off the "Shaded RGB" option, you will simply grab the color with no shading or
baked-in depth. |
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3. After you drag the MRGBZGrabber across the area you choose to sample, Zbrush will very quickly take a snapshot of the area and
split the sample to the alpha menu for the depth and the color menu for the color. To save the alpha grab, select the image in the alpha
menu and then select "export." You'll likely want to choose another directory for the file instead of the default "ZExportImport"
directory, so browse to the directory you want. When saving the snapshot, pick the file format (.PSD,.BMP,.TIF) that best suits your needs. |
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4. You'll follow the same procedure to export the color grab. Select the color snapshot (it's been shuttled to the Texture menu) and choose
"export." Pick a file format and file destination and save the image. |
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5. If you save the depth grab as a .BMP, you will automatically truncate the image from a 16-BPP to an 8-BPP image. If you save the
image as a TIFF or as a .PSD, you'll need to execute a mode conversion. To make the depth grab to a usable displacement or normal map, you'll need
to convert it from 16-BPP to 8-BPP. The easiest way to do this in Photoshop is to select "Image>Mode>8-Bits/Channel" in the upper menu. |
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6. Now that the image is a 8-BPP, RGB color image (it was by default if you saved the file as a .BMP), you can use the image as a displacement map as is
or you can fine-tune the image in Photoshop. You might want to adjust contrast, do edge clean up, or make other changes. If you need to create a normal map,
select "Filters>nvTools>NormalMapFilter." Of course, you need to have the filter (NormalMapFilter.8bf) already installed in your Photoshop "Plug-Ins" directory. |
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7. Depending on the version of the filter you use, you will see a dialogue box similar to the one below. This box allows you,
should it become necessary, to change the normal map light direction by clicking either "Invert X" or "Invert Y" (or clicking both).
You can also ramp up or lower the strength of the normal map by increasing or decreasing the number in the "Scale" box. Play around
with different strengths to get different results. |
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8. If you are satisfied with the image, save it as a .DDS, .TGA, or other file format. |
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This brief introduction should give you an idea of how quickly the depth information created in Zbrush can be translated to usable
art assets for a game engine. |
