How to set the appropriate min and max value of SoDataRange

[East2010]

I create time slice(SoVolumeData,SoDataRange,SoTransferFunction are used).
As you know,
"SoDataRange allows user to specify what range of the data values in a data set (SoDataSet node) should be mapped to the color map"


Now,If I set the min value of SoVolumeData to that of SoDataRange and max value of SoVolumeData to that of SoDataRange,the picture is not good and only change the min and max value of SoDataRange after the slice is created.

I want to know that if there is a method that can caculate the appropriate min and max value of SoDataRang?

By the way,I think the getHistogram of SoVolumeData should be used.But I don't know what to do next.

[mikeheck]

Originally Posted by East2010

Now,If I set the min value of SoVolumeData to that of SoDataRange and max value of SoVolumeData to that of SoDataRange,the picture is not good and only change the min and max value of SoDataRange after the slice is created.

I want to know that if there is a method that can caculate the appropriate min and max value of SoDataRang?

The method SoVolumeData::getMinMax() returns the actual min and max values in the data set. (Note: If the data is in LDM file format, these values are stored in the file header. For other formats, VolumeViz may be forced to load the entire data set in order to compute these values.)

For seismic data these are typically the values you want to use in SoDataRange. Of course there is the possibility that invalid values might exist that are outside the range of valid values. That could result in a bad min or max value for the volume. But usually those problems have been resolved during seismic processing. For 16-bit and larger scanner data (e.g. medical, core sample, etc) it's different because it's common to use a subset of the actual data range (i.e. window center / window width) to enhance brightness and contrast in the resulting image. The histogram can be useful in that case. I'm not sure if the histogram is useful in picking min/max values for seismic, because the peak of the histogram is usually at the center of the range (low amplitude values are most common).

If you can share some information about the volume, the min/max values you're using, and how the picture is "not good", we might be able to make some guesses about what's wrong.

[East2010]

Ok,I explain my question with an example.

I create a segy time slice and set the min and max value of SoDataRange with those of SoVolumeData initially(that is,-27325.00 and 23481.00),and find the color of the section is almost the same(show as notgood.png).

Then I change the min and max value of SoDataRange,and set them -2925.00 and 5766.00 seperately,and find that the slice is colorful(show as good.png).

I think that the majority value of the volume is between -2925.00 and 5766.00.

Now,I want to know how to get the changed value(-2925.00 and 5766.00.) or value near to them initially.