I have to manage a service which can return images in tiff format.
This service is requesting another WCS Service from which it receives the Image File without geo-referenced informations.
So i need to set those informations and particularly tiff Tag field 33550, 33922, 34735 & 34737.
With metadata from WFS service i can use the pootprint and the projection to calculate tiepoints & bounds...
i get field 34737 from my projection (string) ex: WGS 84 / Plate Carree (deprecated)|WGS 84|
i get field 33922 from the foot print (it seems to be always 0.000000,0.000000,0.000000,Upper Left X,Upper Left Y,0.000000
tag 34735: how to know the meaning of all those parameters?
ex: projection epsg:32662 1,1,0,7,1024,0,1,1,1025,0,1,1,1026,34737,35,0,2049,34737,7,35,2054,0,1,9102,3072,0,1,32662,3076,0,1,9001
ex: projection epsg:3857 1,1,0,7,1024,0,1,1,1025,0,1,1,1026,34737,25,0,2049,34737,7,25,2054,0,1,9102,3072,0,1,3857,3076,0,1,9001
how to calculate field 33550 (ModelPixelScaleTag). I supposed it should be based on bounds and pixel width and/or height of the image. But my results is a little bit different from what i should set. (in the wcf service i saved a tiff before and after projection, i used this image (TiffInfo) to check what i have to set in the second service).
Do someone could explain me how to manage & set those fields? (particularly field 33550 & 34735)
TIFFReadDirectory: Warning, Unknown field with tag 33550 (0x830e) encountered.
TIFFReadDirectory: Warning, Unknown field with tag 33922 (0x8482) encountered.
TIFFReadDirectory: Warning, Unknown field with tag 34735 (0x87af) encountered.
TIFFReadDirectory: Warning, Unknown field with tag 34737 (0x87b1) encountered.
TIFF Directory at offset 0x8 (8)
Image Width: 448 Image Length: 418
Bits/Sample: 8
Sample Format: unsigned integer
Compression Scheme: None
Photometric Interpretation: RGB color
Extra Samples: 1<assoc-alpha>
Samples/Pixel: 4
Rows/Strip: 4
Planar Configuration: single image plane
Tag 33550: 155.783428,155.783428,0.000000
Tag 33922: 0.000000,0.000000,0.000000,-1824666.305496,1276523.665790,0.000000
Tag 34735: 1,1,0,7,1024,0,1,1,1025,0,1,1,1026,34737,35,0,2049,34737,7,35,2054,
0,1,9102,3072,0,1,32662,3076,0,1,9001 Tag 34737: WGS 84 / Plate Carree (deprecated)|WGS 84|
Update - more details:
My problematic is:
In one hand I have the image file (stream) associated to a Segment comming from a WCS Service. This image has been reprojected (if requested), but i only get the image without any geo-referenced informations.
In Second hand I have meta-data for this Segment (coming from a WFS Service). Those meta-data include wktBounds, wktCenter, wktFootPrint of the segment in WGS84.
In third hand I have request information --> projection
At the moment when a user requests for tiff Image, the service works with WGS84 tiff Image and set following tifftags:
// Referring to TiffInfo need to set
// Tag 34264 - TiePoints used to georeference image file
// Tag 34735 - fixed value associated to WGS 84 spatial reference system
// Tag 34736 - Ellipsoïd/Spheroid associated to the spatial reference system
// Tag 34737 - Name of spatial reference system
if (tiePoints != null)
{
val34264[0] = tiePoints[0];
val34264[1] = tiePoints[2];
val34264[3] = tiePoints[4];
val34264[4] = tiePoints[1];
val34264[5] = tiePoints[3];
val34264[7] = tiePoints[5];
tif.SetField((TiffTag)34264, val34264);
}
short[] val34735 = { 1, 1, 0, 7, 1024, 0, 1, 2, 1025, 0, 1, 1, 2048, 0, 1, 4326, 2049, -30799, 7, 0, 2054, 0, 1, 9102, 2057, -30800, 1, 1, 2059, -30800, 1, 0 };
tif.SetField((TiffTag)34735, val34735);
double[] val34736 = { 298.257223563, 6378137 };
tif.SetField((TiffTag)34736, val34736);
tif.SetField((TiffTag)34737, "WGS 84|");
The result is that the browser download the geotiff image.
Now i'm trying to adapt this for other projections (3857 and 32662) and calculate TiffTag Fields based on the meta-data of the genuine segment.
