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dchall8
631 post(s)
#07-Mar-18 20:57

Now that we can process DEM files quickly into areas and lines, is it possible to combine DEMs into larger files? I have 1,100 DEM files covering my county. Each one is 17MB. Reading up on images did not help. I tried to copy (Ctrl-A, Ctrl-C) the tiles in one image and paste (Ctrl-V) into another DEM image, but that did not seem to work. Maybe it is not possible at all, but if it is, is it also possible to do it in mass? In another topic it looks like Global Mapper does it rather easily, although Dimitri seems suspicious that corners have been cut in that operation.

tjhb

8,846 post(s)
#07-Mar-18 22:02

Just a quick reply.

There is a specific thread on how to do this with SQL. (I'll find it.)

For copy and paste, remember that the data is not in the image, but in its source table. So to combine tiles, you copy them from one table and paste into a second table--and afterwards adjust the Rect property of the drawing that reads from the second table, to include the pasted tiles.

A but fiddly so far but definitely doable.

Global Mapper remains many times easier for this task for now.

danb


1,708 post(s)
#07-Mar-18 22:17

Thanks Tim, I know we have done this with point clouds and I would be interested to see how to approach it for mosaicking images.


Landsystems Ltd ... Know your land | www.landsystems.co.nz

dchall8
631 post(s)
#07-Mar-18 22:45

That would be nice if it was just a few adjustments to the point cloud import.

Now I'm not getting cut and paste to work for the tile table. I get the warning, Cannot add record.

tjhb

8,846 post(s)
#07-Mar-18 22:50

Good point.

Use Ctrl-Shift-V to paste tiles without source mfd_id (since mfd_id must remain unique in target).

tjhb

8,846 post(s)
#07-Mar-18 23:06

...and...

Dimitri


5,519 post(s)
#08-Mar-18 08:34

I know we have done this with point clouds and I would be interested to see how to approach it for mosaicking images.

Point clouds are vectors/drawings and images are, well, rasters/images. Copy/Paste was a very big deal recently added within 9.0.165.2 for drawings and labels, the relevant notes being:

The map window supports copying and pasting data for drawings and labels. Pasting records between drawings and labels automatically maps fields for geometry and / or text to each other.

Pasting records into a table / drawing / labels automatically converts coordinate systems for geometry fields. The conversion is performed only if both the target and source fields have a valid coordinate system (displayed in black instead of red in the coordinate system pickers, eg, in the Component pane).

So, for now drawings and labels are copy/paste in map windows but not yet images. With images, you can paste tiles into tables and use SQL and otherwise manually work it, but it's not the same as copy/paste within windows for images in a way analogous to what was introduced above for drawings and labels.

There are many issues for images that are wildly different than for vectors, more decisions to make, etc., so that's why the intricacy of the manual steps one now must do if that is desired. Automating all that is much easier after pending additions will be merged into the system so that's why copy/paste for images is coming later.

I agree that fun with contours and tracing is an immediate stimulus to wanting to merge big DEMs into one. It seems like every time you want to contour a DEM for a particular region that it will be exactly bisected by two different data sets you have to download from USGS or whatever. :-)

For now, though, the priority is leaning more towards finishing out all forms of vector manipulation/editing/presentation, with building out all raster capabilities coming a bit later. There are, of course, new raster capabilities like contours and tracing being added (got to have some fun with rasters, after all...) , but the full-bore fun with rasters stuff like seamless copy/paste, pixel level selections and editing and so on will come in the weeks and months ahead.

Have patience and, as always, if you have special preferences for something to be prioritized ahead, speak up with a Suggestion.

tjhb

8,846 post(s)
#07-Mar-18 22:24

Correction:

... and afterwards adjust the Rect property of the image that reads from the second table...

Sorry about that slip.

tjhb

8,846 post(s)
#07-Mar-18 23:09

... No this won't work. What was I thinking?!

The tile indexes need handling too (reindexing), not just the tiles.

Sorry for the brain fade.

Dimitri


5,519 post(s)
#08-Mar-18 08:21

although Dimitri seems suspicious that corners have been cut in that operation.

Curious about that... what's the thread you mean?

dchall8
631 post(s)
#08-Mar-18 14:51

Now I am curious, too. I don't see the comment. Someone mentioned that it was easy to combine DEM files in Global Mapper because the user could drop a folder into a map and they would all open in one layer. Then Dimitri replied and suggested that was risky business because it assumed the answers to a lot of questions such as were all the files in the same projection, etc? Doesn't that sound like you? And where did that line of questioning go? I thought it was on the Cutting Edge part of the forum.

Dimitri


5,519 post(s)
#09-Mar-18 07:57

And where did that line of questioning go? I thought it was on the Cutting Edge part of the forum.

Well, that's something you should know before ascribing words to anyone else.

If you have something to say, say it. Your words are respected as they are, no need to add anyone else as rhetorical salad dressing. :-) If you want to quote somebody else, please quote them exactly so people can find the relevant thread, if they are interested in the original context, by using the search box.

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