Discussion: Open Orienteering Mapper questions

Apologies for using AP for these questions. I've tried the Help and searching on line and looking in a forum, and I can't find out how to do these fairly basic tasks in OOM:

1. What are the steps to take to crop a map (the equivalent of what used to be "Partial Map" in OCAD, and is now, at least in OCAD 11, "Export Part of Map").

2. How do I move a linear object such as a trail? Meaning move the entire object to re-position it, not edit the shape of it. Both selection tools that I try in OOM only allow me to move the position of individual points, thus changing the shape of the object but not moving it as a whole.

Thanks for any help anyone can provide. And if there is some on-line source I can go to for questions like this, that I obviously haven't been able to find, let me know that as well.

1. I have never used the OCAD versions of this, but I think this is what you want. Save a second copy of the map file. On this second copy, take any linear object (I typically use a big pink line), and draw the boundaries of the area of map you want to keep. Go to your edit points tool, and select this object. You should now be able to click the "Cut Out" tool which looks like a small section of map surrounded by a pink circle. It is on the right hand side of the toolbar next to the measure tool. Click this button, and presto. The map is cropped to your selection. Delete the linear object you used as the boundary (for me the pink line), and you're done.

2. Moving a linear object. Use either your Edit Points or Edit Lines tools, and select the object you want to move. When you select the object, the points of the object (blue or grey squares or diamonds), the bezier curves (blue circles), and a purple rectangle surrounding object appear. When you hover over this purple rectangle, it should turn yellow. Click, hold and drag the rectangle - this moves your object. This works for linear objects, areas, and if you zoom in far enough, for point objects as well.

Online Source for Mapper Help- Problems, bug fixes, help, etc. https://github.com/OpenOrienteering/mapper/issues

Hope that helps.

Thanks for the quick response, David.

The #2 item works! I was trying to move a fairly long line (a GPS track that I wanted to reposition slightly), and at first I didn't see the purple rectangle. So I had to zoom out a bit, then I saw it and could move it just fine.

As far as #1, cropping the map, I've drawn the line around the part of the map I want, selected it, and I found the "cut out" tool. It took a bit of trial and error -- finally I saw an instruction at the bottom of the screen that said to make a cutout of the map, now press the Return key. I don't have a Return key but I tried Enter. At first it didn't seem to do anything. I pressed Escape to get out of it and tried again. This time, after I pressed Enter, it finally did the cropping desired. Thanks again for your help.

The extent of my use of OOMapper is to create contours and various lidar rasters, and then to load them up in OOMapper to make sure they all line up. My normal process is to "confuse the cartography program as little as possible", so everything I create has already been reprojected into UTM.

In QGIS, I can specify a default CRS (projection) for a "new" project. In OCAD, I can set real-world coordinates, but it defaults to the middle (zone 31), so I always have to change that. I find OCAD 11 really works well with my "all in one zone" lidar output.

But OOMapper keeps going back to "local" coordinates. The only way I can get stuff to line up is to create a new map, set the zone, load at least one raster, and then import (either ocad or dxf). (I don't do this a lot, so I may be wrong, but that's the only reliable way I can get stuff to line up.)

1: In OCAD (say 11 or 12), is there a way to set default real-world coordinates and a default UTM zone when I click "New / Map"?

2: Is there a way to get OOMapper to stop reverting to its local coordinate system? When I set a UTM zone, that's really what I want to use.

I also recently got OOMapper to work with a Bluetooth GPS on a small Android tablet, but I haven't tried it out in the woods yet.

I'm not much of a mapper, but I process a lot of lidar for mappers. And OCAD 11 works for me. I don't have to play with various orders of loading to get stuff to line up. The only issue I can think of that still causes me trouble on both OOMapper and OCAD is the rotation to magnetic north. I had been advising OCAD users (particularly older versions of OCAD) to just use real-world coordinates and to skip entering the rotation until the end. OOMapper seems to automatically set the Grid-to-Magnetic angle (which it calls "grivation") without too much trouble. Gian-Reto from OCAD suggested it's better to set the angle in OCAD 11 (and 12) before drafting. I'm skeptical of that for people who draft in OCAD 8 and 9, because we keep having trouble with things not lining up.

Would it make sense to tell people to not use these older versions of OCAD for drafting, or to continue with these workarounds to "get it to work".

All of my club's maps are in OCAD format, but only the new ones are georeferenced. We've had a few hobbyist mappers use OOMapper, but the conversions to OCAD cause some trouble. I realized the other day that the CRT capability should let us seamlessly transition between programs by getting rid of the original symbol set and replacing it with symbols native to the other program. Our biggest worry is transitioning back and forth. We want to convert it once, and then maintain it in our program of choice.

With respect to rotation, I have noticed that OCAD can only rotate once. After that the coordinate system seems to get damaged. I try to do any work with GIS/GPS data first, including tracing from aerial photos. After all the "desktop analysis" is complete, the map is rotated to magnetic North, and fieldnotes can be drafted. You can never go back to grid North. Following a defined workflow is good practice.

I think that I've managed to rotate more than once with OOM, as I recall that it was part of the process that I was using for SAR maps and topo orienteering maps.

Here in southern Norway we have had very small offsets between grid and magnetic north for a decade or two (currently it is about 1.5 degrees), so correcting for this isn't extremely critical.

I recommend that all mapping projects should be kept in UTM grid north at all times, and that you export what you need for a given competition/project and then rotate that, but all subsequent mapping work goes back to the original UTM project files.

As several of you have noted, it can be very hard to work with a rotated map in OCAD and rotating multiple times is even worse. I did find OOMs handling of this to be much more intuitive but I haven't tried to see how it handles any exports back to OCAD. I did test that the default OCAD 8 export format (using local coordinates) would still carry along the georef info so that I could switch back to UTM inside OCAD 12.

Terje---Your recommendation to map in UTM grid north is more extreme than I expected, but honestly, it sounds like good advice. It's a really hard sell though. I can't imagine making all the minor edits for an event, and going back each time to do the MN rotation (and fixing all the labels and legends).

The area around me varies from -5 to -7 degrees, but the USA goes from -16 to +16.

What I'd prefer is that the cartography programs (like OCAD and OOMapper) handle it better than they do now. The change in some places is 1 degree every five to ten years, so it's a long-term concern. It would be nice to have automatic MN tools that would handle the rotation as well as actually drawing the MN lines for you with a specific distance (e.g., 250m or 500m) and letting you shift the whole thing E-W for best appearance.

https://www.ngdc.noaa.gov/geomag/WMM/data/WMM2015/...

For Karttapullautin's .ini file and normal UTM Grid-to-MN rotations, I use the "World Magnetic Model (WMM2015) with Stand-alone Graphical User Interface (GUI) for Windows", available here:

https://www.ngdc.noaa.gov/geomag/WMM/soft.shtml

It doesn't show the Grid-to-MN (I think) unless you use UTM as input. I get the UTM coordinates from several places, but the Acme Mapper website with Options set to UTM coordinates works well.

You can copy the UTM coordinates from Acme Mapper (Ctrl-C) and then paste them into the WMMGUI field (Crtl-V). I paste the easting and northing together, then cut the northing out (Ctrl-X) and paste it into the northing field.

In our club we use Condes for all the map layout other than north lines. It makes it much easier to do updates in UTM.

there are usually two components in the process of aligning a map with magnetic north. The magnetic variation is usually quoted as the difference between the magnetic and true azimuths, but most map data is supplied in UTM coords or a similar projection. At the edge of a UTM zone here (NSW 33degree S) there is a grid convergence of about 1.5 degrees ( grid-true). Across the zone boundary the grid convergence is the other way of 1.5 degrees, so the grid to magnetic adjustment value varies by 3 degrees across the zone boundary.
In eastern Australia the zone 55/56 and 55/54 boundaries run right through the middle of some of the major orienteering regions so this is a significant issue for map-makers here.

@rockman---The WMMGUI output does that in one step. It reports grid-to-magnetic based on the 2015 World Magnetic Model. They claim that is current until 2019 (The model lets you enter the date, so it is an algorithm for the period 2015-2019).

The bigger question is: Should you trust the WMM and give it quick check at the map site, or should you do it old school and measure magnetic north at the map site at multiple locations in a serious manner?

What we did for mapant.fi was calculating angle between World Magnetic Model north and grid north for each 3x3 km map tile. Now when user exports map it looks for closest and uses that angle. Here it seems to rotate a tiny bit more than what is usually used in O maps (hand measured or angle taken from national topo maps), but it not too bad and better than nothing.