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#11
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"Tom Jackson" writes:
What do you mean exactly by "After geo-referencing the map files"? Well, maybe my terminology is inaccurate, but what I meant to say was, I load, and calibrate the map image. Nope, your terminology is dead on. Basically, I load the map projection information into the program (i.e., Lambert Conformal Conic, with the appropriate lat/lon info.) I got this information from one of the HTML files related to the specific map TIFF. Stop doing that! The sectionals are already GeoTIFFs. The FAA has already done all of that work for us. (They guarantee 2 pixels RMS error, but I've found distortions much greater than that.) I'm also working on making more easily-digested chunks of data. If you're in the mood to burn some time and bandwidth, you can watch my progress. http://aviationtoolbox.org/munge/mosaic.cgi Just change the extension to ".tif" on any of the images if you want a 5000 by 5000 uncompressed GeoTIFF. (I need to tweak my edge-detection algorithm. When I do, I'll clear those images and start over but you're welcome to try it anyway.) --kyler |
#12
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Maybe I'm missing something -- I'll quickly walk you through what I do in
Oziexlporer: After launching Oziexplorer, I go to the "file" menu, and select "load and calibrate map image" This loads the image, but requires that I supply additional data in order to calibrate the image. There is an additional menu option to "import map", however, GeoTIFF isn't an option. The help screens indicate the following: *******************help text***************************** Geotiff OziExplorer can extract the georeference information from Geotiff files but it only knows how to decode the information if it is from a known source. At this stage only the georeference information in the USA USGS DRG Geotiffs can be decoded. The ability to decode other sources of georeference information in Geotiff files will be added on an as need basis where it is possible to do so. Converting Geotiff Image Files Some Geotiff Image files are in the 24 bit color format. OziExplorer can read 24 bit color TIFF files but must load them fully into RAM instead of paging them from disk as it does with 8 bit color TIFF mages. For large images this requires a lot of RAM. If you convert these files to 8 bit color the Geotiff georeference information is lost. This document describes a technique to save the georeference information and to then put it back into the file. You need Software to convert the Geotiff image from 24 bit to 8 bit color. Paint Shop Pro (www.jasc.com) works well. The Tiff Utilities available from the Utilities section of the OziExplorer web site (www.oziexplorer.com). **************end of help text******************** Perhaps the developer of Oziexplorer needs to add these types of files to its list of "known" types. I will e-mail them. "Kyler Laird" wrote in message ... "Tom Jackson" writes: What do you mean exactly by "After geo-referencing the map files"? Well, maybe my terminology is inaccurate, but what I meant to say was, I load, and calibrate the map image. Nope, your terminology is dead on. Basically, I load the map projection information into the program (i.e., Lambert Conformal Conic, with the appropriate lat/lon info.) I got this information from one of the HTML files related to the specific map TIFF. Stop doing that! The sectionals are already GeoTIFFs. The FAA has already done all of that work for us. (They guarantee 2 pixels RMS error, but I've found distortions much greater than that.) I'm also working on making more easily-digested chunks of data. If you're in the mood to burn some time and bandwidth, you can watch my progress. http://aviationtoolbox.org/munge/mosaic.cgi Just change the extension to ".tif" on any of the images if you want a 5000 by 5000 uncompressed GeoTIFF. (I need to tweak my edge-detection algorithm. When I do, I'll clear those images and start over but you're welcome to try it anyway.) --kyler |
#13
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"Tom Jackson" writes:
Maybe I'm missing something -- I'll quickly walk you through what I do in Oziexlporer: After launching Oziexplorer, I go to the "file" menu, and select "load and calibrate map image" This loads the image, but requires that I supply additional data in order to calibrate the image. It doesn't sound like you're using a TIFF. There is an additional menu option to "import map", however, GeoTIFF isn't an option. Is "TIFF" an option? A GeoTIFF is just a regular TIFF with some standard tagged data. OziExplorer can extract the georeference information from Geotiff files but it only knows how to decode the information if it is from a known source. At this stage only the georeference information in the USA USGS DRG Geotiffs can be decoded. Oh...hmmm...that's a strange limitation. The ability to decode other sources of georeference information in Geotiff files will be added on an as need basis where it is possible to do so. O.k., so OziExplorer is kinda dumb right now. Looks like you get to do it manually for awhile. Converting Geotiff Image Files Some Geotiff Image files are in the 24 bit color format. OziExplorer can read 24 bit color TIFF files but must load them fully into RAM instead of paging them from disk as it does with 8 bit color TIFF mages. For large images this requires a lot of RAM. The sectional maps from the FAA are 8-bit color (palette). I convert them to 24-bit (RGB) when I mask them. The chunks I build are 24-bit. If you convert these files to 8 bit color the Geotiff georeference information is lost. This is just another limitation of OziExplorer. Changing the pixel representation has little to do with the ability to hold GeoTIFF data. I'm planning on making 8-bit versions available but it's easier to manipulate (warp/scale/blend/...) the data without mangling it in 24-bit mode. My preference is to wait until the last step to create the 8-bit images. Software to convert the Geotiff image from 24 bit to 8 bit color. Paint Shop Pro (www.jasc.com) works well. Oh, well sure. *That* will destroy the GeoTIFF data. Perhaps the developer of Oziexplorer needs to add these types of files to its list of "known" types. I will e-mail them. Good luck. I'm sorry I made comments assuming that OziExplorer would deal with GeoTIFFs sensibly. --kyler |
#14
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Please see below from the developer of Oziexplorer - they fixed the software
after I pointed them to your data. It now works amazingly well! ************************************** Hi Tom, I released a new version of OziExplorer today which should import your FAA sectional maps without intervention. Use the Import "All DRG maps on a CD or in a Folder" option. Regards ************************************** "Kyler Laird" wrote in message ... "Tom Jackson" writes: Maybe I'm missing something -- I'll quickly walk you through what I do in Oziexlporer: After launching Oziexplorer, I go to the "file" menu, and select "load and calibrate map image" This loads the image, but requires that I supply additional data in order to calibrate the image. It doesn't sound like you're using a TIFF. There is an additional menu option to "import map", however, GeoTIFF isn't an option. Is "TIFF" an option? A GeoTIFF is just a regular TIFF with some standard tagged data. OziExplorer can extract the georeference information from Geotiff files but it only knows how to decode the information if it is from a known source. At this stage only the georeference information in the USA USGS DRG Geotiffs can be decoded. Oh...hmmm...that's a strange limitation. The ability to decode other sources of georeference information in Geotiff files will be added on an as need basis where it is possible to do so. O.k., so OziExplorer is kinda dumb right now. Looks like you get to do it manually for awhile. Converting Geotiff Image Files Some Geotiff Image files are in the 24 bit color format. OziExplorer can read 24 bit color TIFF files but must load them fully into RAM instead of paging them from disk as it does with 8 bit color TIFF mages. For large images this requires a lot of RAM. The sectional maps from the FAA are 8-bit color (palette). I convert them to 24-bit (RGB) when I mask them. The chunks I build are 24-bit. If you convert these files to 8 bit color the Geotiff georeference information is lost. This is just another limitation of OziExplorer. Changing the pixel representation has little to do with the ability to hold GeoTIFF data. I'm planning on making 8-bit versions available but it's easier to manipulate (warp/scale/blend/...) the data without mangling it in 24-bit mode. My preference is to wait until the last step to create the 8-bit images. Software to convert the Geotiff image from 24 bit to 8 bit color. Paint Shop Pro (www.jasc.com) works well. Oh, well sure. *That* will destroy the GeoTIFF data. Perhaps the developer of Oziexplorer needs to add these types of files to its list of "known" types. I will e-mail them. Good luck. I'm sorry I made comments assuming that OziExplorer would deal with GeoTIFFs sensibly. --kyler |
#15
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"Tom Jackson" writes:
Please see below from the developer of Oziexplorer - they fixed the software after I pointed them to your data. It now works amazingly well! Impressive! I'm still puzzled about why they couldn't handle the GeoTIFFs without special intervention, but I like that they fixed it quickly. BTW, I've finally completed a "chunking" run of all of the sectionals using the "blend" algorithm. I still don't like the way it looks, but I hope others will make suggestions. http://aviationtoolbox.org/munge/mosaic (Damn! They sure do try to make P-49 obvious, don't they?) If you select a chunk, you'll get the full-size (5000x5000) version of it as a JPEG (in another window - always the same one). Change the extension to ".tif" for the GeoTIFF. (Yes, this is just for testing.) The TIFFs compress about 40%. I should be able to do even better if I convert them back to 8-bit (palette) images. More later... It's fun browsing the sectionals. I'd never had one with the note "APPROXIMATE LIMIT OF PACK ICE THROUGH MARCH". http://aviationtoolbox.org/munge/chunked/chunk_8_5.jpg --kyler |
#16
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In article ,
Kyler Laird wrote: BTW, I've finally completed a "chunking" run of all of the sectionals using the "blend" algorithm. I still don't like the way it looks, but I hope others will make suggestions. Wow, I've always wanted one of those. I want to take all the flights I've ever made and plot them on top. Shame the colors don't match. Maybe you could use the elevation key that's on every chart to match between TIFs? -- Ben Jackson http://www.ben.com/ |
#17
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Wow... I was thinking of trying to do this a few weeks ago when you made the
sectionals available. The fact that it's all in GeoTIFF seemed pretty cool, but I didn't quite get around to trying to code something up. How much of a pain will it be to redo it when new sectionals come up? Will you have to re-edit out the non-map area? Thanks again, -Cory Kyler Laird wrote: : "Tom Jackson" writes: :Please see below from the developer of Oziexplorer - they fixed the software :after I pointed them to your data. It now works amazingly well! : Impressive! I'm still puzzled about why they couldn't handle the GeoTIFFs : without special intervention, but I like that they fixed it quickly. : BTW, I've finally completed a "chunking" run of all of the sectionals using : the "blend" algorithm. I still don't like the way it looks, but I hope : others will make suggestions. : http://aviationtoolbox.org/munge/mosaic : (Damn! They sure do try to make P-49 obvious, don't they?) : If you select a chunk, you'll get the full-size (5000x5000) version of it as : a JPEG (in another window - always the same one). Change the extension to : ".tif" for the GeoTIFF. (Yes, this is just for testing.) : The TIFFs compress about 40%. I should be able to do even better if I : convert them back to 8-bit (palette) images. More later... : It's fun browsing the sectionals. I'd never had one with the note : "APPROXIMATE LIMIT OF PACK ICE THROUGH MARCH". : http://aviationtoolbox.org/munge/chunked/chunk_8_5.jpg : --kyler -- ************************************************** *********************** * The prime directive of Linux: * * - learn what you don't know, * * - teach what you do. * * (Just my 20 USm$) * ************************************************** *********************** |
#18
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#20
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