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map calibration.

This is a discussion on map calibration. within the MapPoint Desktop Discussion forums, part of the Map Forums category; I want calibrate (georeference) a bitmap that represent a mappoint map. Is there an algorithm, possibily in c#, for map ...

  1. #1
    PeppeM is offline Junior Member Yellow Belt
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    map calibration.

    I want calibrate (georeference) a bitmap that represent a mappoint map.

    Is there an algorithm, possibily in c#, for map calibration?
    I found a geo-referncing algorithm in codeproject.com ( http://www.codeproject.com/useritems...sp#xx1360144xx ) but this algorithm take only 3 reference point.

    What kind of projection mappoint use?

  2. #2
    Wilfried is offline Senior Member Black Belt
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    Hi,

    Is the article you mention not what you wants ? I think it is good for relative small area's.
    As far as I know mappoint assumes that earth is a perfect sphere.

  3. #3
    PeppeM is offline Junior Member Yellow Belt
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    The small area is good for my work.
    Now I read that mappoint use NAD83 that is ,for small area, equivalent to WGS84 (used by map calibration found in http://www.codeproject.com/useritems...sp#xx1360144xx )

    The only problem is that this algoritm take only 3 point to calibrate raster.
    Three point are few?

  4. #4
    Wilfried is offline Senior Member Black Belt
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    Hi,

    I dont understeand the problem you have. What is wrong with 3 points ?

  5. #5
    PeppeM is offline Junior Member Yellow Belt
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    Are 3 points few for calibration?

  6. #6
    Wilfried is offline Senior Member Black Belt
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    Hi,

    3 points are few enough, you need them for a 2D calculation. But I tought to understeand you had a problem with 3 point ?

  7. #7
    PeppeM is offline Junior Member Yellow Belt
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    Using only three measurements, you have no way of telling whether you made any mistakes, and furthermore using more measurements makes it much more accurate.

    What I need is to use the "least-squares adjustment" (suggested by a thread in a forum) when you have more measurements than initially required.
    This method is very often used for determining affine transformation parameters, I want to find an algorithm that explain how to do it.

  8. #8
    Wilfried is offline Senior Member Black Belt
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    Hi,

    Thank you, I get your point now. I dont know it myself, but maybe someone else know. A quick googling gives alread a lots of info, but as always it is a mess to find the interesting ones. Good luck

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