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need help stretching image
Mark Etheridge from United States  [7 posts]
8 years
I have a lens that has a little over 180deg FOV and I want to stretch the image to make it square. It is on a ccd camera and is not 100% centered up on the imager. I plan to fix this later. Can anyone help me get started on this?

Thanks,
Mark


 
Mark Etheridge from United States  [7 posts] 8 years
I switched the lens to different camera that allowed me to center the lens but the camera is crap. I'll use it for now. I was able to get a decent picture by putting the camera flat on the floor pointing it up at the ceiling. So here is a before and after and the .robo. file. I also posted a new forward looking image without the top being cut off.

This is my first try with roborealm so if this could be done a better way please let me know.

Is there a way to modify the image like I asked in my original post? I would really like to use the camera forward looking and get rid of the black area.

thanks,
Mark


   

program.robo
Anonymous 8 years
Mark,

Actually we have been looking into this. While the polar module works quite well for ceiling point cameras we are trying to adapt the same technique for forward looking. Normally one uses the Radial_Distortion module to correct for these kinds of effects but that is normally used in conjunction with a calibration grid as manually adjusting the different polynomial coefficients can be very tricky.

We are continuing to look into this and should hopefully have an easy to use module to correct the forward looking view somewhat. Note that regardless of the correction there will be some form of warping in the image ... ie in the polar module the resulting floor and ceiling are stretched ... this will most likely be the case in the forward looking too. But the image will be much straighter and more usable regardless.

If you have a chance, take a couple more images with the forward looking view so that we have some more images to test with.

On completion of the module, can we get your permission to use your images in the documentation? I think they nicely reflect what most users would encounter with this kind of lens.

STeven.
Mark Etheridge from United States  [7 posts] 8 years
Thanks Steven,

I'll post some more pictures hopefully in the next few days. I want to find a better camera. I'll take a couple outdoor and indoor. You can use any of the posted photos in your documentation. Let me know if there is anything specific you would like me to capture.

Mark
Anonymous 8 years
Mark,

Thanks for taking more photos. Any photo that includes a lot of straight lines (like a large office building, etc) will be most helpful as the distortion is much easier to see and test for on straight lines.

FYI, we tested your images on some other fisheye correction software ... doesn't appear to work at all well! There is something interesting going on with the lens that you have. Who is the manufacturer?

Thanks,
STeven.
Mark Etheridge from United States  [7 posts] 8 years
Okay, I'll try and get some building shots. I don't know the exact manufacturer of my lens, only that it comes from Asia. Got it from a friend.

There is another lens sold here in the US that looks almost the exact same. Same physical appearance, FOV and F

http://www.omnitech.com/fisheye.htm

There are a couple of example pictures in their data sheet that you could use for testing. Would be interesting to know if you get the same results with their pictures as you do with mine.
Anonymous 8 years
Mark,

Thanks for the find. Omnitech is close by here in Denver!

Ok, in version 2.14.0 we have two new modules that should add to the fun with these images. We've found that for you the Spherical Transform is probably more what you want rather than the fisheye. Try the attached robofiles once you have downloaded the latest version (use the same link as before). It seems to do the trick.

Here are the resulting images:





STeven.

20404_3.robo
program.robo
Mark Etheridge from United States  [7 posts] 8 years
STeven,

Thanks so much for helping with this. That was incredibly fast and the result is awesome. Much appreciated.

Have a Merry Christmas,
Mark

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