I read back posts on this topic, mostly from 2003, and googled too, but have been going around in circles.
Anyone know where I can download free raster topographic maps to use with my own viewer? I’m using OziExplorer.
I haven’t found a free site yet. I’m looking for something like NOAA has for nautical charts, only topo for inland waters.
If nothing already paid for by tax dollars, can you recommend a good commercial CD or download site? I would greatly prefer a one time fee over a yearly membership.
I did find topozone and trails.com. It was unclear to me whether topozone pro allows you to download the raster maps.
Thanks for any leads.
Paul
7.5 minute quads
I would look for a GIS(geographic information system/science) clearinghouse-type website for your state. Most states have them and many offer free USFS 7.5 minute quads for the whole state. These come in a geotiff format to use with GIS software like ArcGIS(very expensive). However, the geotiff acts just like a tiff image file in any image viewer like MS document imaging or MS picture manager that comes with your OS.
you can also
open geotiffs in Paint and modify them and draw new features(trails, campsites, etc) on them.
OK, I got this far.
– Last Updated: Oct-23-07 11:08 AM EST –
Good lead, seumas!
http://www.oregon.gov/DAS/EISPD/GEO/data/format.shtml
Haven't found the actual geotiff files yet. Any help from here?
Paul
try
on left hand menu select “data and maps”
on new page select “spatial data library download page”
on new page scroll down to the "Digital Raster Graphics(DRG) section select “varies” in the e00 size column
This takes you to a directory for the quads. Unfortunately it is in the quad_code format instead of using quad names.
Do you happen to have a state quad index?
have you ever tried google earth
I believe it displays usgs topos
TopoZone
Just FYI…
TopoZone pro does allow download of full USGS mapsheets in .tiff format.
Topozone pro for a yearly fee.
Correct?
Paul
I use google earth, but
if you can view topos, I haven’t figured out how.
Paul
Finding quad index?
OK, needed to click ‘varies,’ thanks! I had done the first two steps, then I clicked on ‘Oregon Lambert Projection NAD83’ rather than ‘varies.’ The lambert project link gave me the URL I posted above. Felt like I was going in a circle.
Haven’t found a quad index yet that I can make sense of. Here’s what I found so far.
http://www.oregon.gov/DAS/EISPD/GEO/docs/metadata/quadindex7_5.htm
http://search.oregon.gov/query.html?col=allore&qc=allore&qt=quad+index
I can get GPS coordinates for the waters of interest, using Googel Earth. Can those be tied to the quads?
Paul
correct
flat yearly fee for any number of 1:24k topos,(also have 1:100K(?) and 1:250K(?) maps included in that package). Quality isn’t too bad, 200dpi resolution, indexed color. Downer is the air photos are not included from what I’ve found.
Another 100 bucks for Photoshop Elements and you can manipulate any standard graphics file at will.
You may need it - these files include the map collars, so if you wish to join multiple sheets you’re gonna need to crop the image.
Cheapest bet is still the geospatial data sites the earlier poster mentioned.
SCROLL THROUGH THIS SITE:
– Last Updated: Oct-23-07 4:35 PM EST –
I kinda think you will be able to find what you need......
http://www.peaklist.org/misc/links_to_map_resources.html
Another site:
http://gpstracklog.typepad.com/gps_tracklog/2005/12/free_usgs_topo_.html
this may seem crazy but
– Last Updated: Oct-23-07 5:02 PM EST –
OK. Here goes. Yes you can figure which quad to download from a set of GPS coordinates. Get them onto dd mm.mmm. The numbers in the first directory on that site are for a block of 64, 1:24000(7 ½ minute) quads. These would be all the quads in that degree of latitude and longitude. There are over 1900 of these quads covering the state of Oregon! For instance the directory numbered 41120 has all the quadrangles covering 41 degree latitude and 120 degrees longitude. That whole degree coordinate(N41, W120) would be in the right bottom corner of the block.
Now draw a table with 8 cells to a side representing this 41120 block. Letters A thru H go up from the bottom for the rows and 1-8 go right to left for the columns. Everything starts at the RIGHT/ BOTTOM of the grid. Each one of those cells represent 7 ½ minutes in both directions.
Example.
41120 A1 will cover from N41 degrees to N41 d 7.5’ and W120d to W120d 7.5’
41120 D5 will cover N41d 22.5’ to N41d 30’ and W120d 30’ to W120d 37.5’
Put the mm.m at the lines dividing the cells of your table. Remember everything starts at the RIGHT/BOTTOM. It will get pretty easy to figure the quad index code after you have done it a few times.
The first directory gives you the block, 41120.
The second directory gets you the Letter code, 41120d.
The third directory gets you to the download 41120d5.
It will come as a zip file. Right click, select extract all and follow the wizard.
In the folder will be a big tiff file and several little files that make it a geotiff(give it a spatial reference). You will only need the tiff if yiy are using it in an image program.
There are easier ways to do this, but they all cost.!
Good luck
Good explanation
– Last Updated: Oct-24-07 2:21 AM EST –
Thanks.
I got close with 43124F1. I was going for Tahkenitch Lake. I got the Umpqua River, just two miles below it. I'll try E and H and should hit it. There was only F1 and F2 for longitude, rather than F1 to F8. http://navigator.state.or.us/sdl/data/DRG24K.html
The map is somewhat tilted when viewing in a picture viewer or in Ozi.
Using the import map command in Ozi, I can view the map, but I don't think it's using the *.tfw file to calibrate. The GPS coordinates on the map don't make any sense and change wildly when moving the cursor over the map. Also, turning on the lat/lon grid doesn't display a grid, another indicator (I think) that Ozi hasn't calibrated the map. If someone here knows the answer, great! Otherwise I'll ask about that at the Ozi discussion group if I don't find the answer in their archives. http://tech.groups.yahoo.com/group/OziUsers-L/
Thanks!
Paul
Thanks for the links.
projection issues
The .tfw file is for full featured GIS. This map is projected in that Oregon Lambert Projection NAD83 which ozi probably can’t deal with. map is tilted because of the projection.
I would highly recommend the National geographic TopoUSA series. You can get a state or a regional package. seamless $100 i think, for the whole state.
more about oziexplorer
I believe you can convert the image into an ozi compatable file. There should be a way, in ozi, to assign coordinates to the corners of the map. Then you should get your grid.
I don’t have ozi so I can’t help with the details, but their website indicated that this was possible.
Best way to get coordinates?
– Last Updated: Oct-24-07 11:20 AM EST –
Yes, I can do a map calibrate by assigning coordinates to at least two points on the map. What's the best way to determine the coordinates of the corners of the map?
I see black grid lines and red numbers (22, 23, etc.)on the map but those numbers seem to be spaced differently than the grid and it's not clear to me that those numbers are labeling the grid. Minute values? I don't have time right now, but later I could bring up google earth and see if the red numbers are approx. right for minute values.
I'm interested to make this work, even for the intellectual exercise to better understand the maps.
I'm starting to agree, a commercial package might be a good idea.
Paul
use the grid
I described to determine the corner coordinates. It really does help to fill the cells and label the lines.
I’ve got to get to work, too. This has been fun!