elevation maps

Started by zu Pferd, May 05, 2019, 10:14:44 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

zu Pferd

In regards to elevation maps, I found this link within Armored Brigade/Matrix
and a handy PDF with step by step instructions to gain at least the gray image to create the
sat elevation in making maps for General Staff
the link is here

and the link to the data also in the PDF.
You need to register to gain the data set.

its a little on the technical side.

Andy ONeill

This is one of the sources I looked into.
There are satellite based elevations on this particular site.
Others also offer Lidar ( laser ) which is more precise.
They give a measurement for a chunk of the earth ( like say a square 500 metres ) with a resolution of +- so many metres.

All are encoded and you either obtain a specific elevation or you get a thing called a geo tiff. This encodes elevation in a sort of a picture.

Unfortunately, significant development would be necessary to make these usable without a lot of manual intervention from the user.
As you can see in the linked pdf.
You would be doing all those processes yourself to get your elevations ready to import.
There is no web service you can call to return an elevation for a specific latitude/longitude.
I found one source is a sort of a hobby site ( could be taken down any time really ).
It is throttled to one call per minute.
We need 1155 * 805
Or 15,496.25 hours.

From the geotiff or dataset you manipulate the data using an open source utility.
What you end up with is a greyscale image.
Which you can import with the current code base.
You can use that process right now.
It has an inherent limit of 255 elevation steps because it uses 255 greyscale.
This is minimum elevation 0 (black) and maximum 255 (white).
For many battlefields that is going to be enough for one step = 1 metre.

What about if that isn't enough though?

If you somehow had a mountain you wanted to include but retain a finer granularity elsewhere then you could potentially blank the mountain higher parts out white.
Set a matching elevation (part way up the mountain) as the upper elevation limit.
Import that image.
Then add the pointy bits back in with a custom greyscale import.
The custom option lets you work with a small image which can contain transparent parts (no change) and is additive.

Which is all very clunky.
But no credit card registration is necessary.

If you're ok with registering a credit card then the google elevation api works very reliably.
They've removed the checks which were intended to stop abuse so it doesn't stop part way through now.
Although this is costed, you get $200 credit a month.
Which covers a lot of maps.

I do understand that the step of registering a credit card is likely to put some off.
It's difficult to get away from the fact that this is a far easier process than the alternatives though.

zu Pferd