<p>This is opengl precision. The solutions I've seen subtract to single precision as you've done. Newer cards, or alternatively specially configured mesa, are potential alternatives.</p>
<div class="gmail_quote">On Jul 11, 2012 6:50 PM, "Richard R McDonald" <<a href="mailto:rmcd@usgs.gov">rmcd@usgs.gov</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif"><div>Hello,</div><div> </div><div>We have an application that provides pre- and post- processing capabilities for computational models of flow and sediment transport in Rivers. The application is built with Qt and VTK. We use both structured and unstructured grids. The grid x,y locations, stored in vtkPoints and set to datatype double, are specified in UTM coordinates. When zooming in close and rotating the the grid, the point locations jump around as if truncated to single precision. Using the same data sets with a subtracted offset to bring the x,y locations down to single precision eliminates the problem. Can anyone lend some insight as to why this might be happening? Is there a truncation issue in VTK or is it a product of the graphics board? Any help would be greatly appreciated. </div>
<div> </div><div>Thank you,<br></div><div>Rich McDonald<br>Research Hydrologist<br>USGS Geomorphology and Sediment Transport Laboratory<br>4620 Technology Drive, Suite 400<br>Golden, CO 80403<br><a href="tel:303%20278%207952" value="+13032787952" target="_blank">303 278 7952</a><br>
<a href="mailto:rmcd@usgs.gov" target="_blank">rmcd@usgs.gov</a><br></div></font><br>_______________________________________________<br>
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