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

1. Originally Posted by RobA
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>
I took another look at Gimp's Python requirements and found that I was missing the pyGtk. Even with that corrected (Python-fu now shows up in the filters list) the first "measure active path" .py I downloaded didn't work. I moved on to the script you suggested and it does work. I have to determine the scale of distance units per pixel and perform some calculations, but it's still better than guessing.

Originally Posted by Redrobes
We talked before about measuring the amount of area within a map and we came up with a cool method which was really fast . . . . Multiply by pixels per m scale and thats real length on map.
This works too. I used a 1 pixel wide brush and then I just took the number of black pixels and multiplied by pixels per mile (we still love our imperial units here in the U.S.).

Is there any need to use a brush wider than 1 pixel when determining length?

2. Originally Posted by CyrusStonecypher
Is there any need to use a brush wider than 1 pixel when determining length?
Not really if PS counts the pixels up. Mine showed a percentage black or white. By using thicker brush it was more accurate cos mine was something like 0.7% or something. With a 10pix wide brush it went to 6.7%. Also if you get the odd crooked bit of line then it matters 1/10th as much. If you cross over lines then you would have to compensate a bit tho cos you have missed one crossing points worth.

Also if you use a square brush instead of a round one then it will naturally compensate for travelling at 45 degrees where your covering 1.4 x as much distance per pixel as going horz or vert because the square brush stretched out at 45 deg is wider than a round one.

3. Originally Posted by waldronate
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.
Hrm. I thought that was a straight line measurement (the little Ruler icon). Unless, of course, there is another update that I've missed.

GW

4. Originally Posted by Carnifex
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.
Wouldn't that just place each number one tab's length away from the previous number's end, and not from the centre of the previous number? That is to say that once you start getting into double digits especially, it'll offset it quite badly.

I know that you can overlay an image onto google earth, and you can use that to measure distances. It's rendered entirely useless if your map is not of an entire world, of course. If you've got a world map, however, it should work fine. If you know Earth's dimensions and you know your own world's dimensions, it's a simple ratio change. You could even place the continent map onto Google Earth and find somewhere that is supposed to be roughly the same size as this place (unless you don't know. In which case, I'm sorry I'm being useless here. :s).

5. Originally Posted by VincentAlliath
Wouldn't that just place each number one tab's length away from the previous number's end, and not from the centre of the previous number? That is to say that once you start getting into double digits especially, it'll offset it quite badly.
No, the tab's length are from the START of one set of numbers to the the START of the next set of mumbers. Just like a regular tab works in MS Word etc.

6. Originally Posted by Greason Wolfe
Hrm. I thought that was a straight line measurement (the little Ruler icon). Unless, of course, there is another update that I've missed.GW
To quote from the status bar message for FT's ruler tool: "Left click to start measurement, Shift+Click to add segment, Click again for distance readout". For spherical worlds it's great-circle distance; for planar worlds it's planar distance. The path consists of as many little segments as you'd like to click while holding down the Shift key and they are all summed at the end.

7. Originally Posted by waldronate
To quote from the status bar message for FT's ruler tool: "Left click to start measurement, Shift+Click to add segment, Click again for distance readout". For spherical worlds it's great-circle distance; for planar worlds it's planar distance. The path consists of as many little segments as you'd like to click while holding down the Shift key and they are all summed at the end.
See, that's what I get for paying attention. Bwahahahaha!

GW

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