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Microsoft KB Archive/172828

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HOWTO: The 50-Pixel Polygon Shading Metric

PSS ID Number: Q172828 Article last modified on 09-05-1997




The information in this article applies to:

  • Softimage 3D for IRIX, version 3.7
  • == Softimage 3D for Windows NT, version 3.7 ==


The 50 pixel polygon shading is a performance metric used by manufactures to benchmark their systems (they draw triangles that they know are exactly 25 or 50 pixels in size). In SI3D, when you draw a triangle, the size of the triangle, in screen space, is incidental. It depends on many factors – the camera parameters (zoom, position, or interest), the window resolution, the size of the objects, the angle at which you are viewing them (edge-on versus perpendicular to them), etc.


You can perform the following steps to get an approximation of how fast your card can draw 50-pixel triangles pixels:

  1. With a 1280 x 1024 version of SI3D running, maximize the top view and set it to Shade.

  2. Get->Primitive->Grid, Polygon, X size 1.0, Z size: 1.0, X Cell Count: 77, Z Cell Count: 77. Frame selection (f).

    The grid should now occupy about 60% of the full screen in the horizontal direction (768 pixels) and 75% of the screen in the vertical direction (also 768 pixels).

  3. Click playback to get an approximation of the frame rate (around 13fps).

  4. Multiply that number by 11858 to get the approximate number of 50-pixel triangles per second. Remember that you also have the extra overhead of SI3D – you are not just drawing triangles. So, this can likely give significantly lower results than a vendors’ benchmark; they are measuring one specific thing under very specific conditions.

If the frame rate is too high (more than 25fps or 30fps), then the accuracy of the measurement will not be very accurate. You can also use SI Live for frame rate statistics.


If you have any questions concerning the information contained in this article, contact by e-mail.

Additional query words: si si3d si3dhard si3dui

Keywords : si si3d si3dhard si3dui Version : IRIX:3.7; WINDOWS NT:3.7 Platform : IRIX NT WINDOWS Issue type : kbhowto kbinfo ============================================================================= Copyright Microsoft Corporation 1997.