virtualnobi's profile - activity

Steven, thanks a lot for this answer. It'll take a while to take that in... I already stumbled across the LatentSVM thingy (whatever that means :-) so maybe I'll try that first. I don't really want it exotic, just working ;-)

I'm not an expert on CV, but I guess you will get more responses if you are more specific in your question: What exactly did you do (i.e., executed which programs using which data)? And what exactly is your error message (copy and paste text)? (By the way, did you google for the exact error message?) Thirdly, what did you expect to happen instead?

@StevenPuttemans Thanks for the clear statement, but - since I am new to computer vision - can you give me some pointers to "non-rigid" models? I thought the pedestrian, face, cat, etc. recognition videos found on youtube were created with this technique... wrong assumption?

@bio_c, that's what I tried (I think ;-) Unfortunately, we have Black Angus, which don't differ much from their shadows, and as far as I've seen, color is anyway reduced to greyscale, isn't it? The "copy-paste of True groups into photos of varied fields" is done automagically by the opencv_createsamples program, I figure - or what would you use? I prepared samples with (trial, comic cow) positives on transparent background, but the opencv_createsamples would ignore the transparency in the positives so that the samples still don't show the silhouette nicely....

@berak, thanks for the hints. I saw your answer to the linked question, but our photography is from above, so the cow is seen only from above (neck and back), instead of the front view shown in the linked question. I'll try to add a sample positive.

Since I was not getting good recognition results (on aerial photography of cattle on fields), I tried to use transparency in the positives, to let the cows stand out more. Ultimately, I want to count the cows on the image.

But using transparency is a dumb idea, it seems, and I would just like to confirm that

• transparency in the positive images is ignored by the createsamples and traincascade tools
• only the -bgcolor and -bgthresh of createsamples determine what is considered transparent

Is that correct?

The problem I see is that the background of the positive cow images vary a lot (gras vs. sand, gras texture, etc.), so I will have an issue specifying a single -bgcolor. Before I set out to mask the background, I'd like to know how to do it correctly.

Thanks, nobi

EDIT: Here are samples of the images I use:

Overview of field, from which cows (and calves) should be counted (cropped):

Positive image, extracted from one of the overview images:

Resulting sample file (since .vec cannot be uploaded, this is a screenshot of a .vec file):

The sample file is not one created from the positive image - because opencv_createsamples renames the files, I cannot easily find the corresponding one.

What you can clearly see in the sample file is the background of the positive, which could lead to the (very) low recognition rate (actually, zero).