[FWTools] Help with LCC georeferencing and reprojection
randre at gmail.com
Thu Oct 9 20:07:01 EDT 2008
Sorry, looks like I can't include the file with the image in it. If you run
the steps I sent, and create a file called "test.tif", you can dump the text
below in an editor and save it to a file as "test.kml" in the same directory
as "test.tif" .
On Thu, Oct 9, 2008 at 4:54 PM, Roger André <randre at gmail.com> wrote:
> Hi James,
> Spent some time trying to gereference the file using the corner coords that
> you provided, but had absolutely no luck. One thing you could try that
> might work better is to defin some Ground Control Points. Basically you can
> pick features on the image that you can identify on another map, and record
> the lon lat and pixel x y positions. Then you use gdal_translate to assign
> the GCP's to the image, and finally use gdalwarp to warp the image to fit
> the GCP points.
> Here are some rough ones that I used on the sample you sent me:
> - gdal_translate -gcp 171 320 -76.864698 43.943184 -gcp 818 23 -70.410805
> 47.178880 -gcp 804 473 -69.829644 43.706997 flight_chart.tif
> - gdalwarp -s_srs "EPSG:4326" -t_srs "EPSG:4326" gcp_flight_chart.tif
> I've attached a KMZ file of this, you can see that it's not perfect, but if
> you work with the higher resolution image, and assign more GCP's it should
> start to bet pretty close.
> To go immediately to spherical mercator, you'll have to convert the points
> you find into spherical mercator coordinates, and then use EPSG:900913
> instead of 4326.
> On Thu, Oct 9, 2008 at 9:54 AM, James Trimble <jimmit.t at gmail.com> wrote:
>> ** I apologize if this message appears more than once, but it does not
>> look like it's going through for me **
>> Hi, I am trying to georeference and reproject an FAA Enroute IFR chart.
>> You can find the pdf version of this chart at
>> http://www.jamestrimble.info/US <http://goog_1223485636161/> L32 31 JUL
>> I use The Gimp to convert the pdf to png.
>> The parameters are
>> L-32 1:14NM (1020787)
>> GP 47 56 09.6N 063 04 30.3W (Upper Right)
>> GP 46 02 46.4N 079 29 47.0W (Upper Left)
>> GP 41 48 34.9N 078 00 33.5W (Lower Left)
>> GP 43 35 36.2N 062 37 08.3W (Lower Right)
>> Top Standard Parallel 45 00 00N
>> Bottom Standard Parallel 33 00 00N
>> Central Meridian 95 00 00W
>> Origin 39 00 00N 95 00 00W
>> Datum = North American Datum of 1983
>> Ultimately, I'd like to have this map in a mercator projection to overlay
>> with google maps.
>> The commands I tried to use are :
>> gdal_translate -a_srs "+proj=lcc +lat_1=45.0 +lat_2=33.0 +lat_0=39.0
>> +lon_0=95.0 +datum=NAD83" -a_ullr -79.4964 46.0462 -62.6190 43.5934 -of
>> GTiff -co "INTERLEAVE=PIXEL" "C:\Documents and Settings\James\Desktop\US L32
>> 31 JUL 08_CROPPED.png" .\USL32.tiff
>> gdalwarp -of GTiff -co "INTERLEAVE=PIXEL" -s_srs "+proj=lcc +lat_1=45.0
>> +lat_2=33.0 +lat_0=39.0 +lon_0=95.0 +datum=NAD83" -t_srs "+proj=merc
>> +datum=NAD83" .\USL32.tiff .\USL32_MERC.tiff
>> I would really appreciate some help on how to do this correctly.
>> Thank you very much,
>> FWTools mailing list
>> FWTools at lists.maptools.org
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