Scale conformity between FT3 and CC3+?

kmunoz

I use FT3 to create world maps and export chunks of them into CC3+. I'm noticing that the correct scale doesn't seem to be retained, so that all the distances are wildly off. Is this just a function of the way the exporter works (i.e., it doesn't worry about scale) or is there something I can do in a setting to fix this?

FWIW, the scaling issue goes both ways. Sometimes, an FT3 map will show a body of land being 100 miles across but CC3+ makes it 400 miles across. Other times, an FT3 map will show a body of land being 3,000 miles across but CC3+ makes it 500 miles across.

Loopysue

That's an interesting point, actually. I've never really thought about it to be perfectly honest, since I tend to worry about the size of the export a lot more than the size of the map on the screen in CC3. (That's probably because my computer tends to crash if I use the top resolution export from FT3, because its pretty useless - the laptop, not the app).

I don't think there is an actual relationship, but if its important to you that the export should be a certain size in CC3 you can always show all sheets, select all, and scale it larger, once you have it in CC3.

Not sure I've ever tried going the other way...

Monsen

The scale should be correct, but note that the scale bar placed by FT3 is usually not correct, you can't rely on that for showing the scale.

Another thing that throws a spanner into the works is map projection. FT3 does provide measurements correctly over a globe, while any export to CC3+ will be projected to a flat plane, which does cause some inaccuracies for the scale, since a sphere cannot be correctly represented on a flat plane.

kmunoz

I'm not even using the scale bar as a reference. I'm using distance measurement tools. The numbers are way, way off. When I get home from work today I'll attach the files for reference and you'll see what I mean.

kmunoz

Posted By: LoopysueThat's an interesting point, actually. I've never really thought about it to be perfectly honest, since I tend to worry about the size of the export a lot more than the size of the map on the screen in CC3. (That's probably because my computer tends to crash if I use the top resolution export from FT3, because its pretty useless - the laptop, not the app).

I don't think there is an actual relationship, but if its important to you that the export should be a certain size in CC3 you can always show all sheets, select all, and scale it larger, once you have it in CC3.

Not sure I've ever tried going the other way...

I use FT3 because I am a stickler for precision. Scaling the CC3 map essentially by eyeballing it is doable but not a satisfying solution.

Loopysue

The only way that you will ever be able to transfer between the two apps with perfect accuracy is by creating a flat world.

That's because FT3 works (most usually) on a spheroid world and all the alternative projections, which distort distances in every direction and to different degrees depending on the projection, while CC3 makes no allowances for the curvature of a spheroid world and shows constant scale in all directions - as you would find on a flat world.

Monsen

Posted By: kmunozI'm not even using the scale bar as a reference. I'm using distance measurement tools. The numbers are way, way off.

Interesting. All the exports I've made have had the scale work fine, distance tool gives me about the same in both FT3 and CC3+. A little bit of a difference, but that is to be expected because map projection issues.

I'll try out your files when you attach them to see what I experience there. Will probably be tomorrow though, midnight is fast approaching.

kmunoz

Link to zip with three files: https://tinyurl.com/y9tgb4br

(Don't know how to make the attachments feature work.)

FT3 file: go to the Nations: Seven Kingdoms view, get the N/S distance of the top middle body of water. Comes to around 600.
CC3+ file "Seven Kingdoms": The distance is around 90.
CC3+ file "raw test": The distance is around 900.

Maybe I did something in the "Seven Kingdoms" file to make it 10% the distance of the raw test (I made the map a year ago, I don't remember), but the raw test file shouldn't be producing distances 150% the size of the FT3 file. If anything the distances should be shorter, since it's not measuring along a curve.

kmunoz

...I discovered the problem. It's the orthographic projection in FT3 that I was using. I assumed that at a small scale the warping when flattened for CC3+ wouldn't be that significant, but it is. I get much closer results when I go to equirectangular in FT3 - a difference of only about 20 miles on a 600+ mile measurement.

So! The answer to the conundrum is to switch to a flat projection in FT3 *before* exporting to CC3+. You were of course right in your original comment!

Carry on.

jslayton

You're using the Orthographic map projection, which has severe area and angle distortions. Different map projection have different properties; http://progonos.com/furuti/MapProj/Normal/TOC/cartTOC.html is a good source for learning more about these properties.

http://desktop.arcgis.com/en/arcmap/10.3/tools/coverage-toolbox/choosing-a-map-projection.htm offers some suggestions for picking a map projection which will be a good compromise between the different kinds of distortions.

EDIT: and that's what I get for taking a long time to compose a message...

kmunoz

Yes, I discovered the problem shortly after posting my link.

I was led astray because my original, worked-up map is *severely* off in scale, far more than would be explained by the differences in projections. But it looks like I must have done something to that one that scaled it down to 10% of its original scale, since the raw test map is 10x bigger in scale. But before I realized that problem it really did look like the scale was off, since even a switch from orthographic to a flat CC3+ map wouldn't have resulted in a change from 600 miles to 90.

Once I fixed that problem, the scale discrepancy got better, and then I noticed that my FT3 map was in orthographic.

Edit: and that's what I get for doing exactly the same thing, just now.

jslayton

With an Orthographic projection, if you get your center of projection in the center of your export area and your map doesn't cover a large part of the globe, then the distortions generally won't be too bad. If, on the other hand, you get your center of projection far away from the center of your export area, the distortions will get worse as your maps moves away from the center of projection.

You can move the center of projection on your map by using the hand tool and holding down the Shift key (but I suspect that you already know that).

Maelstromm

On a somewhat unrelated note . . . Can you export files created in CC3+ into FT3? If so how well do the projections come out?

jslayton

FT3 does not directly read the native file format of CC3 (*.fcw files). Long ago Ralf wrote a tutorial for converting a CC2 file into an image and then importing that image into FT ( http://www.jhendor.de/tutorials/cc2-ft.pdf ). Much of this information is still relevant, but FT3 allows direct import of image overlays, which makes the conversion step simpler.