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Discussion: Tablet Mapping x 2?

in: Orienteering; General

Mar 11, 2020 11:59 PM # 
Lots of orienteering mappers extol the wonders of taking a tablet in the field to do their mapping. Many love that there is no transfer needed to the 'good copy' once you get home. Nothing gets dropped. That sounds good to me.
But what if you have a large area and to save time two or more people people each with their own tablet are doing the fieldwork or it is one with a tablet and another using a gps device backed up by good old mylar and pencils.
How do the various bits of work get merged into one map?
Mar 12, 2020 2:54 AM # 
My experience is that I find it hard to draw to an acceptable standard in the field with a tablet. My current project is a 60 hours/sq kilometre terrain. Clean drafting is crucial. The tablet keeps me focused on choices about generalisation as I can see on the tablet problems as they emerge. But I redraw at home to get better quality drafting. This is particularly the case with challenges like close spaced embankments where I want the tags to line up sensibly. Taking this approach means I cover more ground in the field on a given day and then can concentrate on drafting in the comfort of home.
If a team was working on a map, I would think each could be responsible for redrawing their work on a shared drive such as Google, dropbox or onedrive. Not sure how one achieves mapping consistency though.
Mar 12, 2020 3:49 AM # 
Yeah our experiences of having two (or more) people map an area is with lack of consistency across mapping styles. We have (or had) a map that had three people cobble together bits of it and you really could see the differences between the different mappers.
Mar 12, 2020 8:10 AM # 
Mapper 1 works along the boundary while mapper 2 works away from it. Once M1 has finished the boundary section, M2 opens that as a background map (or prints a basemap with that work on it) so (s)he can match up accurately. When both have finished simply import M2's file into M1's file, or vice versa.
Mar 12, 2020 9:50 AM # 
I don't know if anyone's tried this on a real map, but in theory OOM makes this dead easy with its native .omap format - which is just XML.

If you started with the same base map, which has the same colours and symbols, then the actual map data is just a collection of tags:

<object type="1" symbol="99"><coords count="46">-106940 36850 1;-107700 36870;-107700 38040;-108460 38060; ...etc...;</coords><pattern rotation="0"><coord x="0" y="0"/></pattern></object>

Any good file comparison program, eg. WinMerge for the windows junkies, should be able to merge two or more of these files without even blinking.
Mar 12, 2020 1:20 PM # 
So Juffy I don't understand what all of that says but I don't have to, right.
Would this work?
I open and start the map in OCAD 2019
Send a duplicate of the file to my mapping partner for his use on his tablet
He does his fieldwork and I do mine, both in different sections of the map.
When we are done our fieldwork we use that WinMerge to bring his program back in to mine and original data such as contours and trails from the base map will not be duplicated.
Is that how it goes?
If we work in the same section and one adjusts a bit of contour for example and the other doesn't it gets messy, no?
Mar 12, 2020 1:41 PM # 
There's a difference in mindset between the traditional way of working where there was a basemap, and everything that goes onto the final map gets redrawn, and the "new" way where the basemap objects are just modified and added to as needed. I think most of the experienced people here are thinking in the traditional way. (As do I.)
Mar 12, 2020 1:48 PM # 
Gord, if do it the way I suggest you don't have to fool around with stuff like that that you don't understand - it's just everyday stuff in OCAD.
Mar 12, 2020 2:12 PM # 
@gordhun - with a bit of manipulation via OOM it would work. If you both edit a bit of the same feature then it *may* pick up the changes properly but I feel like it's going to get sketchy. :)
Mar 15, 2020 10:35 PM # 
Craig W and I mapped 6-7 sq. km. of Pound Ridge for the 2016 champs, each using a tablet. For various reasons the approach robplow suggested couldn’t be used for this project. Here’s how I periodically merged Craig’s drafting with the master map I maintained:

... Create a new line symbol, to be used only for cutting in portions of Craig’s map.

... Using that symbol, carefully outline the area of Craig’s map to be cut into the master map.

... Edit that line symbol so it is as narrow as possible. This is like making the knife sharper.

... Export that outlined section of Craig’s map to a temporary file.

... Export that outline–the line alone–from Craig’s map to a temporary file.

... Import that outline into my master map.

... Use that outline, and OCAD’s Cut-a-hole function, to cut a hole in the master map. (Cut-a-hole is found under Objects>Crop Objects.)

... Import the portion of Craig’s map saved in the temporary file into the master map. It fits exactly into the hole that was cut.

It probably sounds more complicated than it is. I found that after a couple of times, I could do it pretty quickly and cleanly.

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