The SegmentMeanShift raster function only takes 3 band 8 bit input. It was developed originally for RGB images. Add the ExtractBandFunction first to pick the 3 bands you want to use. This can be RGB, but you can also create a false color image using the IR band + 2 other bands. It depends on the task, what you want to do or classify in the end. Choose the 3 bands such that things you want to distinguish later are as different in color as possible. On top of ExtractBandFunction, add SegmentMeanShift function and it should work fine.
If you have input 16 bit not 8 bit, add Stretch function to scale pixel values down to 8 bit.
In general, play with ExtractBands and Stretch and their params until you like the intermediate, 3 band 8 bit false color image. Then apply Segment on that result.
The Segment gp tool is more forgiving. Main reason is other gp tools also allow many bands many bits on input. Price to pay is we get some inconsistency between Segment gp tool and Segment raster function.
Hope that helps. Best, Tom.
