I don't recall you getting an answer to this... Perhaps if you can attach a small data file that shows this behavior it would help. Also, have you tried casting your data from byte to float or vice versa to pin down the source of the problem? you can use Compute to do that. I created a very simple program and didn't see any problem per se with Band and byte data, so it may depend on something specific to your data. Essentially band creates abutting polygons that define the "bands" of the quantized data. Each polygon then gets the data value for that band, dependent on connections. That's why you no longer see interpolation of colors. I'm a little confused by your statement that "showpositions and showconnections don't work". They should work just fine on the output of Band.
Donna L. Gresh, Ph.D. Visual Analysis Group IBM T.J. Watson Research Center (914) 784-5049 http://www.research.ibm.com/people/g/donnagresh [EMAIL PROTECTED] Sharon Gibson <[EMAIL PROTECTED]> To: [email protected] Sent by: cc: [EMAIL PROTECTED] Subject: [opendx-users] Band module son.ibm.com 05/15/2002 01:46 PM Please respond to opendx-users Is anyone aware of problems or "features" of the Band module ? I began experimenting with the Band module because I thought that it might offer a convenient way to scale float data into discrete byte values for the purposes of utilizing "delayed" colors. It did work nicely for that, but I see that it has the additional effect of eliminating interpolation between colors in the rendering of scattered points. For my purposes, I consider that a big bonus ! However, I am finding that the results are not perfect in every case. In particular, when I band byte data (scaling not required, but I'm banding it so that it looks like the other data sets when rendered), there are regions within the image that are black (as if no data). It looks to me like there is some kind of polygon filling algorithm run amok. The regions that are colored (not black) look fine (similar to the original, unbanded data), but they are outlined with the color that would, if correct, correspond to the adjacent, black areas. This scenario hints at an algorithm that tries to estimate a polygon but closes it inward (forming an outline around an existing "blob" rather than outward, to form a new blob. Strangely, I see no problem with the banded data if it originates as float. Or maybe the important factor is that the float data has a larger range - the byte data has values only 0,1,2. How can I eliminate the black areas ? How does this module work ? I see that whatever it is doing, it changes the positions/connections somehow (can't later use ShowPositions !)
