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Thread: How can I measure travel distance on electronic maps?

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    Question How can I measure travel distance on electronic maps?

    (My apologies if this isn't in quite the right place. I"m new to Cartographer's Guild.)

    I have a scanned image (.pdf) of a commercially published fantasy map which shows the better part of a continent. I would like to measure travel distances between points on the map. Straight lines are easy, but roads and rivers aren't straight.

    I can't find a way to measure non-straight lines in Photo Shop CS3. (Doesn't mean it can't be done just means that I can't figure out how. )

    I found a plug-in for GIMP that "measures active path" but the download is in Python. I went so far as to install Python and use a utility to turn the .py into an .exe, but no dice. GIMP does not like it.

    I've become so obsessed with finding a solution that I've considered using GIS software and creating a false data set for the map. (This should be a clue as to my current mental state.)

    I hope that my mind is merely clouded by my obsessive state and a simple solution exists. Please, please help!

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      Coyotemax is offline
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    I've just started looking but so far I've found the following standalone application:
    http://www.exefind.com/universal-des...er-P17811.html

    and the following, which involved Illustrator:
    "However, if it is absolutely critical that you have the complete length dimension of a curved path... export the path to Illustrator and use it's Measuring Tool (it measures the curves correctly)."

    My finished maps
    "...sometimes the most efficient way to make something look drawn by hand is to simply draw it by hand..."

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      RobA is offline
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    Quote Originally Posted by CyrusStonecypher View Post
    I found a plug-in for GIMP that "measures active path" but the download is in Python. I went so far as to install Python and use a utility to turn the .py into an .exe, but no dice. GIMP does not like it.
    You need to have gimp with python installed to run a python plugin.

    It is trivial to do in scheme, however, I can write up a real quick Path Length script if you want for Gimp, that does not need the python install. (Can't help with PS, sorry).

    -Rob A>

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    Well, I would say that all you can do is take a best guess approach because not only are there turns and curves to navigate but there are also hills and valleys to navigate so getting a totally accurate number is just about impossible. So the way that I do a best guesstimate is to take a 100-pixel brush tip and set the spacing to 100% Then just draw a line following the path and count how many dots are there and multiple that by 100. You could use say a 10-pixel tip or whatever is needed.
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    What if you write numbers along a path in photoshop - separating them with tabulators?

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    Quote Originally Posted by RobA View Post
    You need to have gimp with python installed to run a python plugin.

    It is trivial to do in scheme, however, I can write up a real quick Path Length script if you want for Gimp, that does not need the python install. (Can't help with PS, sorry).

    -Rob A>
    Are you saying that Gimp needs to have some sort of python plug-in or just that Python must be installed on my system?

    A Path Length script for GIMP would be awesome! (I'm not partial to PS, I just gave it a try because it's there. )

    Quote Originally Posted by Coyotemax View Post
    I've just started looking but so far I've found the following standalone application:
    http://www.exefind.com/universal-des...er-P17811.html

    and the following, which involved Illustrator:
    "However, if it is absolutely critical that you have the complete length dimension of a curved path... export the path to Illustrator and use it's Measuring Tool (it measures the curves correctly)."
    I took a look at the Universal ruler. It's a little clumsy, but it is functional. The scale must be reconfigured if the map zoom changes. Thanks for finding it.

    I don't have Illustrator. Thanks for the info though.

    Quote Originally Posted by Ascension View Post
    Well, I would say that all you can do is take a best guess approach because not only are there turns and curves to navigate but there are also hills and valleys to navigate so getting a totally accurate number is just about impossible. So the way that I do a best guesstimate is to take a 100-pixel brush tip and set the spacing to 100% Then just draw a line following the path and count how many dots are there and multiple that by 100. You could use say a 10-pixel tip or whatever is needed.
    That's not a bad idea!

    Quote Originally Posted by Carnifex View Post
    What if you write numbers along a path in photoshop - separating them with tabulators?
    I . . . umm . . what? LOL. My Photoshop skills are minimal and I'm a cartographic newb.
    Last edited by CyrusStonecypher; 02-11-2010 at 07:52 AM.

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      Carnifex is offline
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    Quote Originally Posted by CyrusStonecypher View Post

    I . . . umm . . what? LOL. My Photoshop skills are minimal and I'm a cartographic newb.
    Can you make a path in Photoshop? Select the Pen tool. Click where you want the path to begin and then click where you want it to end.

    Next select the Type tool and click in the beginning of the path. Now you can write on the path. Wite a number (probably "0") and then press the tab key once. Write another number (probably "1"). Continue until you're satisfied. The numbers should now be evenly distributed along the path.

    With the Pen tool you can add more anchor points on the path.

    Then use the Direct selection tool to select and move those new anchor points.

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      RobA is offline
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    Quote Originally Posted by CyrusStonecypher View Post
    Are you saying that Gimp needs to have some sort of python plug-in or just that Python must be installed on my system?

    A Path Length script for GIMP would be awesome! (I'm not partial to PS, I just gave it a try because it's there. )
    You need python installed, and gimp installed with python support to use python plugins. It isn't simple in windows, but I can point you in the right direction if desired.

    regarding a script, Fencepost has a path animation script suite (scripts here, tutorial here) that includes a "Path Details" function (right click on a path and select Path Details that will give you the length in pixels, the number of points and the closed status.

    -Rob A>

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      Redrobes is offline
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    We talked before about measuring the amount of area within a map and we came up with a cool method which was really fast. I think the same can be applied to a length of path too.

    If you create a new layer on top of the map and then draw with a known pixel width brush like 10 or 20 pixels wide in connecting solid lines - i.e. not dots - in black. Then once done you take the map layer and fill it solid white so that you have just a black and white image. No greyscale - contrast enhance 100% if you have to.

    Now the nice feature PSP and Gimp has and I am sure PS has is this histogram window where if you hover your mouse in the histogram then it tells you how much as a percentage of the screen is white or black. So take number, multiply by image width x image height and that gives number of line pixels in image. Then divide by the 10 or 20 for the line width and that gives line length in pixels. Multiply by pixels per m scale and thats real length on map.

    Rob did you ever Gimp up that area script ? If you did then its just area / 10 or 20 depending on the line width.

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    I vaguely recall that ProFantasy's Fractal Terrains Pro has a path measurement feature. The big problem there, of course, was getting the map aligned in the right projection and place on the globe in the first place.

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