Re: Measuring angles in an image.

On Apr 26, 9:22 am, Geobird <a1chan...@xxxxxxxxx> wrote:
I  don't yet have the  knowledge on optics and can't go into it's
depths  but  I will have to swim across these rivers .  It  is now bit
clear to me that  spatial calibration
holds  good  for measuring angles  and  for distances I resort to
single  plane.
Yet what I think , we are counting the pixel difference  and  finding
distance in that  plane.
Though I don't have deeper understanding of image matrices, i would
like to ask. If you break an image into matrix of numbers , can't a
pixel hold discreet values that can in some way correspond to the
distance from the camera .

-----------------------------------------------------------------------------
Geobird:
Yes it can, but only if you have prior knowledge. For example, there
are stereoscopic, interferometric, and profilometry systems that will
give you range/topographic information. Even many medical imaging
systems (CT, MRI, ultrasound, etc.) will give distances in the z
direction. But if you have just some general photo, then no. For
example if I have a photo of you standing on the banks of the Hudson
River, I can't tell you from the photo alone that you are standing 30
feet from me, Manhattan is 5000 feet from me, the jet in the sky is 10
miles from me, and the sun is 93 million miles away from me. You need
some other information, just gray levels or color values, and pixel
(x,y) position is not enough.
Regards,
ImageAnalyst
.

Relevant Pages

  • Re: contour shading
    ... Determine the level at the current pixel, ... Locate two distance measures to the level below, ... to use a 2d pixel traversal algorithm which tested a "ray". ... If the ray hit a pixel with the desired level, ...
    (comp.graphics.algorithms)
  • Re: 11x14, no way??
    ... > Let's all not forget that the normal viewing distance is a consideration. ... I Have been disappointed time and again when I have seen a large photo ... This is the test I did when I was looking at how much resolution I ... Scale the first image for the print ...
    (rec.photo.digital)
  • Re: color threshold
    ... I mean i arrange lind of window which take only colors which is inside in this window. ... Rest color pixel dont count in my program. ... The way I have tackled this in the past is to use the concept of colour distance. ... Use this binary mask and apply to your original image, you will find that the only pixels left are those which meet your colour range criteria. ...
    (comp.soft-sys.matlab)
  • Re: The megapixel insanity continues
    ... photo with a camera with sufficient resolution or with a panorama ... Pixel count matters. ... than the ability to scrutinise the print close-up (group photo ...
    (rec.photo.digital)
  • Re: Saving a Path as a BMP
    ... Is there a way to get photoshop to enlarge the pixel size of the ... chosen in the pencil selector (2nd row of icons on top)? ... instance, my photo is 100X200 pixels coming in, and I blow it up 4X so ...
    (comp.graphics.apps.photoshop)