Changes between Version 30 and Version 31 of MapGuideRfc51


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Timestamp:
Nov 18, 2008, 10:33:02 AM (15 years ago)
Author:
tonyfang
Comment:

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  • MapGuideRfc51

    v30 v31  
    9797Autodesk
    9898
    99 == Addendum ==
     99== Addendum 1 ==
    100100
    101101When we came to implement this proposal, it became apparent that it would be more efficient to generate the grid in the raster coordinate system and transform it into the map coordinate system, rather than the other way round (as originally proposed). A description of the new method follows:
    … …  
    116116||Figure 3. The raster image is rendered into the viewport using the transformation mesh.||
    117117
    118 --------
     118== Addendum 2 ==
     119
    119120Regarding:
    120121||We will add an optimization if the re-projection is a simple datum shift. The image will simply be shifted, and the advanced algorithm will not be invoked.||
    … …  
    122123Upon further investigation, it is not correct to shift the image when the re-projection is a datum shift. Transformations are not that simple. The advanced algorithm will be invoked for all CS transformations.
    123124
    124 --------
     125== Addendum 3 ==
    125126
    126127If the !RasterGridSize is close in size to the actual width or height of your image (e.g. a !RasterGridSize that is ~50% of the height/width), and the raster re-projection is more than a simple affine transformation (e.g. LL84 -> World-Sinusoidal), then you will end up with a poor raster re-projection.