Hello,

I'm assuming you're scenario is this:

1) You run cmvision, and get valid blobs
2) You cover your camera, and get the error

I believe this is a bug where we are not clearing the list of blobs.

Quick thing to try:
open cmvision_color_blob_finder.cpp in $(cmvision)/src

look for:
// Get all the blobs
blob_count = 0;

Add this line right below "blob_count = 0;"
blob_message_.blobs.clear();

-nate

On Mon, Sep 20, 2010 at 6:47 PM, Jin, Li <li_jin@brown.edu> wrote:
> Hi All,
>
> I have a question about cmvision package. When I looked at the blobs msg by
> "rostopic echo /blobs", I got things like this.
>
> header:
>   seq: 466
>   stamp:
>     secs: 1285021814
>     nsecs: 952005043
>   frame_id: ''
> image_width: 640
> image_height: 480
> blob_count: 0
> blobs:
>   -
>     red: 0
>     green: 255
>     blue: 0
>     area: 14494
>     x: 403
>     y: 168
>     left: 348
>     right: 462
>     top: 40
>     bottom: 310
>   -
>     red: 0
>     green: 255
>     blue: 0
>     area: 364
>     x: 459
>     y: 107
>     left: 444
>     right: 475
>     top: 59
>     bottom: 159
>   -
>     red: 0
>     green: 255
>     blue: 0
>     area: 41
>     x: 476
>     y: 50
>     left: 462
>
> My question is, why the blob_count = 0 but there are blob info in the list?
> I am especially curious about the one with area of 14494.
>
> Sorry if it is a noob question.
>
> Thanks.
> Li
>
>
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