12-23-2009 02:45 PM
Hello,
I am trying to construct a polar intensity plot. There are a lot of different solutions on the board but 3D graph and pixel by pixel plotting won't cut it for the update time I am looking for.
Think 'weather radar'
My current solution is to use replacePixelLine.vi. I place one end of this line in the center of my picture, and sweep the other end around in a circle. My pixel color data is my intensity levels, I switch data sets everytime I move into another angular bin. Its quick enough to update every ~25ms, which is good for me.
However there is a bad side effect in replacePixelLine.vi that makes all of this pretty much useless. When the line must step diagonally, it moves 1 pixel in both x and y directions, instead of making an L by moving in x, then y. This means that at 45 degrees, this vi draws only 71% of the pixels as 0 degrees. On top of this, instead of scaling the pixel color data, it just lops off what it cannot plot.
Therefore I have a strange situation where my data is plotted in a squarish shape and the angular bins don't 'arc' correctly. The bins are just drawn as straight lines, either horizontally or vertically depending which side of the n*45deg lines you are on.
Is it possible to change internal workings of replacePixelLine?
12-28-2009 10:06 AM
12-28-2009 11:29 AM
Hi pschmal,
replacePixelLine.vi is not a VI that is shipped with the Vision Development Module. I assume you are using the IMAQ Get Pixel Line and IMAQ Set Pixel Line within a subVI that is named replacePixelLine.vi. Is this true?
Is it possible for you to post a bit of sample code that demonstrates what you are having problems with. It is easier to diagnose and come up with possible workarounds that way. Thanks!
Kristen H.