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Observation about FS using WGS84 GeoLatLon = bad textures

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I have observed for some time that what ever gets processed thru the SDK tools never comes close to that which is done through other tools.Looking at the result of an outputed WGS84/LatLon image sutable for the SDK tools and then compare the result after the textures are made for FS you can see that the image is squished from output by GIS only then be resampled and expanded back to a somewhat "normal" looking texture, resizing aspect ratio and then resizing aspect ratio again is never good as details are lost. Expand 50-100%, change aspect ratio once and then resize back down would be one thing, but to do what we are doing to good data (aspect resampled twice)is bork to image quality.I'm going back to older slicing tools that allow for 1024 textures and then using MW graphic tools to convert as this makes no sense.Does anyone follow me here? Just look at any textures that FS is really using for photoreal, none are as squished as the reprojected data is when it have to do WGS84/GeoLatLon.Is this some bad old idea from times long ago from FS5 and no one ever thought to change?Look. Im putting it out there not to bash anyone, just these seem to be what I am seeing, perhaps I am borked?

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Hi there,how exactly are you saving your images, what tool and with what parameter settings?FS will "squish" or "stretch" images in the longitudional axis depending on the latitude. I seem to remember that the latitude of least distortion is at about N42 and S42. That's due to the fact that FS9 uses a flat area projection rather than a sphere.Cheers, Holger

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>Hi there,>>how exactly are you saving your images, what tool and with>what parameter settings?>>FS will "squish" or "stretch" images in the longitudional axis>depending on the latitude. I seem to remember that the>latitude of least distortion is at about N42 and S42. That's>due to the fact that FS9 uses a flat area projection rather>than a sphere.>>Cheers, HolgerHi Holger,I probably am not explaining this correctly but I

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The sim does not resample, or reproject anything. It's taking a lat-long wgs84 image ( required ) and stretching/compressing it to fit a curved surface. GlobalMapper allows you to alter the pixel spacing of your exported image, and that may help preserve color or contrast if you make that smaller. In other words, it forces an export that has more pixels per degree, thereby making the image larger and giving resample.exe more pixels to work with .If there's any image degradation, you can most likely blame it on GlobalMapper's reprojection routines.Dick

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What you "see" displayed in Global Mapper does not necessarily represent the full resolution of the data -- take a look in an image program. I took some NY state SPCS NY West data for Rochester (source was in SID unknown compression quality 1 ft resolution) saved it as geotiff and then loaded that. Then reprojected it leaving the default resolution and unchecking (square pixels) and again exported geotiff. My SPCS tiff was 13607x9459 and after reprojecting to geo, the new tiff had the same dimensions. scott s..

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Hi Scott and Dick,Yes exactly, Take a look in an image program of the saved GeoTiff and it is compressed from the north and south or expanded east to west.I am not saying the Sim is altering this, I am saying that resampler is and why? As the >final resulting image data/textures are no longer stretched/compressed.Unstrecthed data > global mapper > reproject= Streched/Compressed and export as > GeoTiff Still=Stretched/Compressed as seen in PhotoShop > run through Resampler = Un stretched/uncompresseed data is the result of the data as viewed before or not in FS.Again I am Saying it goes say from being "square" data to "rectangle" only to have Resample make it "square" again, FS is not really using a true WGS84 LatLon rutine or not?

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What I am saying is that the "compressed" appearance is strictly a result of how the pixels are mapped on your display. The actual data is exactly the same size (but it is slightly rotated which results in some loss of data). I think the actual data in the sim use latitude in meters and longitude in "pseudodegrees" .scott s..

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"What I am saying is that the "compressed" appearance is strictly a result of how the pixels are mapped on your display. The actual data is exactly the same size (but it is slightly rotated which results in some loss of data). I think the actual data in the sim use latitude in meters and longitude in "pseudodegrees" ."Thanks for the reply Scott,I disagree with you though, if I open up ANY data such as the GeoTiff in PhotoShop or any other program as outputed from Global Mapper in the "required" GeoLatLon format, It is still "compressed" only after resample is done with it does it look "right" again. The rotated part is not a concern as that has remained and is necessary, but the compression is not remaining >After< Resample, thats why I have brought this up, tis un-necessary.You are saying your Outputed data after your GIS has reprojected is not compressed?

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Hi there,resampling the source UTM image into geographic lat/long does not significantly alter the content of the source it simply increases (or reduces) the width of each pixel in the longitudional axis in order to fit the data into the new projection.If you're concerned about how your original image looks in Photoshop (which is irrelevant for the display in the sim, as you've noticed yourself) then you can use the "Always Generate Square Pixels" option in the export window of Global Mapper. I believe it's active by default so try saving your image with the check box off.Cheers, Holger

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I must be realy dense... (yep) From what your saying and what probably everyone has been saying is if the image data data was say 30000x20000 in pixels the data is still 30000-W x 20000-H but pixels are no longer normal square so that it >appears< as though it has changed to say: 40000-Wide x 20000 high.?Is that it? Just pixel values have changed?

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Hi there,that sounds about right.An image in UTM projection will have pixels with equal dimensions in both axes, say 5m.Resampling to Geographic lat/long translates those dimensions into the correlating span of arc degrees lat and arc degrees long. The ratio of lat/long depends on the latitude, and in the mid northern latitudes the longitudional dimension of each pixel is about twice that of its latitudional dimension: hence the *apparent* stretching or squishing effect. Key is that the information itself is not lost.Here's what the GM manual says about the Square Pixels option:"If the Always Generate Square Pixels option is checked, the smaller of the specified x and y resolutions will be used for both the x and y resolution. Forcing square pixels ensures that the resultant GeoTIFF file will look good even in software that is not able to deal with pixels that aren't square."Cheers, Holger

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Well Tanks for the patience with me guys in clearing that up.Armed with this

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