Hello,
I am using paraview 5.6.0 but have noticed the following issue already in version 4.3.1: the colors representing my .vtu or .vtk data are not exactly agreeing with the one shown in the color legend. The colors of the color legend are always slightly lighter. In the figure i pasted, the red and blue values at the edge of the color legend (20 and 850) should exactly represent the values of the red box on the right side and the upper blue stripe respectively. I have already tried changing the opacity values, the background color (white), the number of tables in the color legend as well as different color presets. But the problem remains.
I would be grateful for any advice.
Best regards,
Tine
Tine,
The short answer to your question is that lighting is effecting the brightness of the colors painted on your data. Lighting is, of course, quite important when understanding shape and orientation in a 3D environment. A side effect is that it will effect the brightness of the colors being displayed. (You might be surprised how much your visual system expects and corrects for this.)
If you are using ParaView 4.3.1, you can edit the lights to make the brightness correct for flat objects facing the camera. In the Properties panel there is an advanced View option called Lights. Click the Edit button under that and in the resulting dialog box turn off Light Kit and turn on Additional Headlight.
In ParaView 5.6.0 the controls have changed a bit. (I don’t remember when the transition happened.) You get to similar controls by going to the menu View -> Light Inspector. From there, just turn off Light Kit. This will turn off all lights and put ParaView in a no lighting mode, which will give you the exact colors you want.
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Great, issue solved, thanks for the quick reply!
Sometimes, I do want lighting for some objects but not have it affect the color representation of some others (e.g. a slice).
Turning off the Light Kit is not an option for me then.
One can then still control the lighting via the Ambient and Diffuse settings in the Lighting Options of the particular object.
On the left:
On the right:
As a bonus one can play around with these parameters to achieve a good compromise between color representation and sense of three-dimensionality when dealing with 3D-shapes.
The former setting should give you an accurate color representation, or am I mistaken?
I would like to know though: Is it possible to achieve the same effect with Ray Traced Rendering activated? I.e. switch off lighting for a particular object and have its surface represented exactly according to colorbar?