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Merging 7.5 topos?

Posted: Fri Jul 27, 2012 11:49 pm
by mokelumnekid
Maybe this is the wrong forum for this- but I'd like to merger various 7.7 topos (downloaded from HST as tiff) but am wondering best way...tried in Illustrator and they too big for that it seems. Suggestions welcome.

Re: Merging 7.5 topos?

Posted: Sat Jul 28, 2012 9:59 am
by whiteout
I use GIMP. I bet it could handle this situation.

Re: Merging 7.5 topos?

Posted: Sat Jul 28, 2012 10:10 am
by giantbrookie
I have done this both for hiking and for geology purposes. I have tended to do this in Illustrator, too, but as you note the file sizes can get enormous and lead to near paralysis even with a really robust computer.

If trying to really use two (or more)full quads the file size issue is particularly daunting. I have never had a need, though, to have multiple complete quads joined--usually I'm looking at some area on the borders (either for hiking or geology), and I've joined up to four maps (the "four corners" scenario) before, although they were by no means four full 7.5' quads. What I do is I trim the quads to be joined to the smallest size in Photoshop (physical size by cropping to what I need and file size by saving as .jpg and adjusting the "quality" and, at times, the dpi/ppi) possible before placing in Illustrator, joining (and possibly doing some other manipulations such as moving in a scale bar, a few representative long, lats, etc into the map area, given that I've trimmed those off earlier). I then usually export this out as .jpg for printing (much smaller file).

For an easily accessible .tif map stash, I use Libremap.org (complete 7.5's of every map in USA, I believe), although their scanned tiffs tend to require a bit of rotation (usually between 1 and 1.6°) to make them truly squared to N-S.

I don't know if the way I'm doing it is the best way and I'm interested to hear what some of the more computer-savvy folks say (because I'm certainly pretty clueless myself), but in any case the above strategy has worked for me (with the caveat that I haven't done this with multiple complete quads).

Re: Merging 7.5 topos?

Posted: Mon Jul 30, 2012 10:26 am
by SSSdave
mokelumnekid wrote:Maybe this is the wrong forum for this- but I'd like to merger various 7.7 topos (downloaded from HST as tiff) but am wondering best way...tried in Illustrator and they too big for that it seems. Suggestions welcome.
Where are tiff's on HST?

Have been using Photoshop or Gimp for years to merge 7.5m topos I download from libremap, I then print out.

Re: Merging 7.5 topos?

Posted: Mon Jul 30, 2012 12:08 pm
by copeg
SSSdave wrote:Where are tiff's on HST?
See the HST Map with 7.5' Topo selection enabled.