USGS Topoquads Out of Alignment (GM v14)
paulp575
Global Mapper UserTrusted User
Here I go again - trying to load the USGS topoquads and they are not aligning up properly.
According to the website where I downloaded them from, here's what it says:
The USGS developed digital quad grids at 1:24000, 1:100000 and 1:250000.
These grids contain the quad reference number and name as maintained in the USGS Index to topographic
and other Map Coverage books or Catalog of topographic and other Published Map books. These individual
zip files are in an ArcView shapefile format and in the following projection:
projection Lambert Azimuthal Projection
units meters
major axis 6370997.00000
minor axis 0.00000
radius of the sphere of reference 6370997.00000
longitude of center of projection -100 0 0.00000
latitude of center of projection 45 0 0.00000
false easting 0.00000
false northing 0.00000
Here's what I've previously used when adding to GM:
Projection data for use in GlobalMapper:
Projection Lambert Azimuthal Equal-Area
Datum Clarke 1866 Authalic Sphere
units Meters
longitude of center of projection -100 0 0.00000
latitude of center of projection 45 0 0.00000
Here's the source of this information: http://data.geocomm.com/readme/usgs/grids.html
In version 13 they loaded correctly. However, in v 14 they are not as you can see from the attached screenshot.
What should I be using for the projection?
Thanks,
Paul
According to the website where I downloaded them from, here's what it says:
The USGS developed digital quad grids at 1:24000, 1:100000 and 1:250000.
These grids contain the quad reference number and name as maintained in the USGS Index to topographic
and other Map Coverage books or Catalog of topographic and other Published Map books. These individual
zip files are in an ArcView shapefile format and in the following projection:
projection Lambert Azimuthal Projection
units meters
major axis 6370997.00000
minor axis 0.00000
radius of the sphere of reference 6370997.00000
longitude of center of projection -100 0 0.00000
latitude of center of projection 45 0 0.00000
false easting 0.00000
false northing 0.00000
Here's what I've previously used when adding to GM:
Projection data for use in GlobalMapper:
Projection Lambert Azimuthal Equal-Area
Datum Clarke 1866 Authalic Sphere
units Meters
longitude of center of projection -100 0 0.00000
latitude of center of projection 45 0 0.00000
Here's the source of this information: http://data.geocomm.com/readme/usgs/grids.html
In version 13 they loaded correctly. However, in v 14 they are not as you can see from the attached screenshot.
What should I be using for the projection?
Thanks,
Paul
Comments
-
What is the site where you actually got the quad grid lines? Typically the quad lines themselves are relative to NAD27 or NAD83, but there is certainly a good amount of other USGS data that is relative to Clarke 1866 (Authalic sphere). If you load other data sources from the File->Download ONline Imagery/Data menu command does it line up with the topo maps?
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
global_mapper wrote: »What is the site where you actually got the quad grid lines?
Thisweb apge: http://data.geocomm.com/catalog/US/group127.htmlglobal_mapper wrote: »Typically the quad lines themselves are relative to NAD27 or NAD83, but there is certainly a good amount of other USGS data that is relative to Clarke 1866 (Authalic sphere). If you load other data sources from the File->Download ONline Imagery/Data menu command does it line up with the topo maps?
I'll try that, but wanted to continue to use something I'm familiar with.
Thanks,
Paul -
global_mapper wrote: »If you load other data sources from the File->Download ONline Imagery/Data menu command does it line up with the topo maps?
Didn't see anything in the online catalog.
I'm looking for a file that shows the specific USGS topoquads quadrangle names. The files on the above cited page show the 24k/25k, 100k, and 250k quad names.
Paul -
Paul,
I just downloaded the 24K topo grid and loaded it in GM14 then loaded a 24K DRG on top and it aligned perfectly in v14 (see screenshot). I didn't even have to provide a projection, I just loaded the QUAD24.ZIP file directly and the projection was automatically loaded just fine. Are you being asked for a projection when loading your topo quads themselves?
gm_screenshot.png
Thanks,
Mike
Global Mapper Guru
gmsupport@bluemarblegeo.com
http://www.globalmapper.com -
global_mapper wrote: »Are you being asked for a projection when loading your topo quads themselves?
I was, but decided to re-download the three USGS topoquads files. Apparently they have changed something because now they are loading correctly - with being prompted for a projection.
I noticed the files inside the ZIP file are dated 2008; mine were dated 1999.
Problem solved!
Again, awesome support - thanks,
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