On May 31, 2005, at 2:07 AM, IOhannes m zmoelnig wrote:
The last outlet is for the Z axis and, as near as I can tell, the code
whatever "Z" means. it definitely knows nothing about the z-axis in a 3dimensional space.
The variable is labeled m_zOut throughout the source code. It sure looks like an attempt to map magnitude of the image brightness to the Z axis to me, but then again I didn't write the thing.
measures how bright the image is by dividing the sum of all of the selected channels by the maximum possible sum for the image. So if the image was entirely white (R,G,B all = 255) it would give a 1.0 and a black image would be 0.0.
so the last outlet is a measure of the size of the blob. if you use [pix_movement] to convert motion (== change of data in a series of images) into an image (the difference between the sequence of images), then the blob-size is a measure of the amount of movement (between to subsequent images).
so the blobsize is somewhat like the overall "brightness" of the blob.
I wasn't trying to contradict anything, but rather explain how the object came up with that value. It's sometimes helpful to know that sort of thing.
using [pix_background] instead of [pix_movement] _could_ produce better results, but i think this really depends on your set up. if you are not sure, experiment with both and see what gives better results
pix_background would come before pix_movement and strip away data which could potentially cause false triggers.
well, if he does "NOT want to TRACK anything" but just detect if there is any movement in the image, your suggestion seems to be a bit overpowered (nonetheless it should work fine)
pix_movement + pix_blob give me enough false values that I recommend using additional analysis to give more consistent results. That's all. Sorry if that wasn't made clear from the start.
cgc