Colors, Ranges, Shading and Light Sources with White Background

Last Reviewed: 05/27/1999

Article ID:


Long Description:
With the growth of the user base on NT platforms, more users are using direct screen capture utilities rather than Postscript to save their graphic displays. Normally a white background is desired ( or at least something other than black ).

It is fairly common knowledge that the best way to do this is to go to the Display/Color_Palette menu and change white to black and vice versa. To do this, make sure the HLS option is selected, then click on the black box at the top of the spectrum and drag the lightness slidebar to 1.0. Then click on the white box near the middle of the spectrum and set the Lightness to 0.0. If you didn’t know this, now you do. But, this cascades through several layers of display attributes.

Problem 1:

If you create a shaded image, it is either very dark or doesn’t show up at all depending on your graphics engine. This is because you are now shining a black light on your model.

Go to Display/Light_Sources.
The top box of this form tells you which light sources are posted, or currently illuminating your model. The next item going down the form is Target_Light_Source. This allows you to select and modify any of the existing light sources as well as delete them or create new ones. For now, we just want to modify the ones you have. If you select one of the currently posted sources and check the color box lower on the
form, it is probably now black. Click on the color box and change it to white or any other color you wish and hit apply. The intensity of the source can also be controlled with the slide bar below the color box. Remember that he actual displayed color will be a blend of the light source and shade color on the Display/Entity… form, so if you want to do some fancy light source settings, you may want the entity shaded in white. Check the online help if you want to look at the other options on the form.

Problem 2: My fringe plots now have this ugly black band.

Option 1, go back to the Color Palette and make the black a shade of gray by setting the Lightness to something you can live with.

Option 2, create a spectrum and fringe range with one or more fewer colors. Go to Display/Spectrums and hit the Create button. Enter a name and select 15 or fewer colors. If you select 15, it will just knock the black off the bottom. You can now pick the different spectrum colors and reassign them from the color table if you wish. Then hit apply to create the new spectrum. Now go to Display/Ranges and hit Create.
Enter a new Range name and the number of sub-ranges to be one less than the number of colors in your new spectrum. If the new spectrum is currently selected, Patran will do this for you. Now hit the Assign_Target_Range_to_Viewport button. If you currently have a fringe plot displayed, hit the Fit_Results, then Calculate, then Apply buttons. Otherwise, just Cancel out of the form and the new spectrum and range settings will be used in subsequent fringe plots.