On Thursday 07 November 2013 15:19:26 edgar did opine: > Am Thu, 7 Nov 2013 13:26:14 -0500 > > schrieb Gene Heskett <ghesk...@wdtv.com>: > > Hello all; > > > > I, and several others are attempting to make use of camera vision in > > a machine shop environment, to auto position a lathe or milling > > machine for instance. > > > > My current camera is the highest priced of the logitech webcams, with > > a nominally 5 megapixel format. > > > > But for our purposes, the field of view at 2540x19xx is at least 75 > > degrees. We need maybe 5 degrees because all we are interested in is > > the pixel under the center pixel of the crosshairs. This, when > > inspecting the workpiece from 50mm, should represent accuracy's in > > the thousandth of an inch category, and would generally be quite > > useful to us. > > > > So, is it possible to setup a framebuffer with 2 circular pointers, > > the input pointer writing the 5 megapixel image as it comes in, and > > an output pointer that only reads out the central 100x100 pixels of > > the image, maybe even 240x240 but for our uses its overkill. > > > > The problem as it exists now is the processing time for the video > > image to get thru camview-emc and actually be presented on our > > computer screens, is on the order of 3 to 5 seconds when the whole > > signal chain has to deal with the 2540x19xx format of a decent > > webcam. If we could throw away all but the mathematical central area > > of the image that the rest of the video chain had to process using > > only 1 core of a 1.4Ghz atom processor, it seems we could save many > > valuable seconds of image processing time. > > > > The V4L list didn't understand what I wanted, so everything they > > suggested threw away resolution which we don't want to do, and gave > > the same field of view in the output, but converted to useless fuzz. > > Hence I come here in search of help. Effectively, we need extreme > > telephoto at maybe 57,600 pixels (240x240 for this example) > > resolution, captured pixel by pixel from the central 57,600 pixels of > > the input for this application. > > > > Thank you for any usable suggestions. > > > > Cheers, Gene > > This is a job for a camera with a telephoto lens. > You're using a camera with the wrong lens, that's all.
Several reasons not to. 1. Such lenses may be available where you are but just asking about them at stores where I can buy the camera gets me a "telewhat?" 2. Mechanical alignment, quite important, depends on the precision they use to mold the plastics. And is generally non-repeatable. 3. Costs several times what the camera costs. 4, throwing away the unwanted pixels should be a few lines of code, essentially free, and by reducing the amount of data to be processed from 5,000,000 pixels to 57,600 pixels gains me only .0868% times the data to process, which gains me many frames a second in processing speed, something your lens cannot not do. > > For many cameras there are telephoto adaptors. And how many can focus to 20mm from their front element? > Capturing 2540x19xx pixels to get a 100x100 picture is > an extremely unreasonable approach. > Considering the cost of your alternative, its a most reasonable approach. A run what ya brung approach to be sure, but if it gets the job done, who cares if I throw away roughly 95% of the picture? Any body else? Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) "It's in process": So wrapped up in red tape that the situation is almost hopeless. A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. _______________________________________________ xorg@lists.x.org: X.Org support Archives: http://lists.freedesktop.org/archives/xorg Info: http://lists.x.org/mailman/listinfo/xorg Your subscription address: %(user_address)s