Mapper: Reference point

[ollesmaps]

Steps to reproduce

When setting up a new file, you shall georeference map.
As it is now, you have to find coordinates somewhere else and copy /paste them into Map georeferencing dialogue box.

Expected behaviour

1. Let user open OpenStreetMap
2. Let user zoom in on desired location
3. Copy URL
4. Paste URL into Mapper
5. Mapper scrapes geographic references from that and sets up a reference point.

Configuration

Mapper Version: 0.8.0.
Operating System: Win

[krticka]

Maybe good idea to add one step:

1. Round the local coordinates to the nearest thousands of kilometre grid

[yevhenmazur]

Why do you think that copy-paste the URL it is better then copy-past the coordinates itself? On the sly I see only cons of this concept...

1. It doesn't work offline
2. Now I can get coordinates from any source I want, like paper map, or other georeferenced map or from OSM URL :)
3. For example my parents doesn't know what is URL, but they are familiar with geographical coordinates, because they learned it in school.

[jmacura]

@yevhenmazur As I understand it, this should be an optional other option (but maybe the prioritized one), besides setting the coords of reference point manually.

I would rewrite the steps 3–4 of Olles's proposal to single one:

1. Let user pick a point in the zoomed area of the map

Maybe it's obvious but this is only useful if the OSM opens within the Mapper (in separate window, in a fullscreen, somehow, doesn't matter). If it only forces the web browser to open with prefilled location, it's value added is equal to zero.

[puzzlepaint]

Are you aware that Mapper suggests a reference point when you load a georeferenced template (for example, an .osm file exported from OpenStreetMap) in a non-georeferenced map (verified with version 0.8.1)? Since, for a new map, one probably also wants to load at least one georeferenced template to make use of the georeferencing, this allows to do both of these steps at once (loading the template and specifying the georeferencing), without having to copy any reference point coordinates from somewhere else. The georeferencing is then set up while loading the template, and one only needs to choose a coordinate reference system and look up the declination in this step, since the reference point is already pre-filled with the center of the template.

[ollesmaps]

@yevhenmazur I like the simplicity of a similar tool Lookup declination (also in the Map Georeferencing dialog box). As @jmacura writes, it should be optional. You should still be able to write it there "manualy" (as you can with declination).

I also like the proposal of @jmacura that OSM shall open within the Mapper, so there is no need for copypasting.

@krticka proposal to round the local coordinates to the nearest thousands of kilometre grid sounds reasonable. A question to that: Is it "just" eye pleasing measure or has it a deeper need later?

@puzzlepaint I am aware of it. However you do not always have georeferenced basemaps (especially newcomers) available. Additionaly I prefer to adjust declination first and then load other basemaps,

[ollesmaps]

Just to clarify my motivation further. I was lately helping to write a Start up kit - how to make a sprint map for Regional Youth and Developmnet Commission IOF. It should be very condensed manual with links to other recources. To give you an idea bellow is a draft of part of Mapping chapter.

1. Prepare on desktop .omap file for fieldwork with Android phone/ tablet.
   The .omap file shall contain all aquired base maps (either as bitmap or vector templates). This will enable you later during fieldwork to switch between base maps and derive from them as much information as possible.

2. Make sure your .omap is georeferenced (usually in UTM coordinate reference system), so you can use the power of GPS in your Android device. UTM coordinate reference system can be used all over the world, however UTM zones are different with different longitudes.

3. Set your georeference. Go to OpenStreetMap and zoom into your location. The tail of the URL now contains geographic coordinates.

4. Fill these coordinates into “Geographic coordinates”. Push “Calculate” button and your UTM zone will get calculated (see picture).

...

[yevhenmazur]

Are you aware that Mapper suggests a reference point when you load a georeferenced template (for example, an .osm file exported from OpenStreetMap) in a non-georeferenced map (verified with version 0.8.1)?

Cool feature! Thanks. Unfortunately it doesn't work for raster georeferenced templates with world file. I've created a separate issue - https://github.com/OpenOrienteering/mapper/issues/1133.

[krticka]

@krticka proposal to round the local coordinates to the nearest thousands of kilometre grid sounds reasonable. A question to that: Is it "just" eye pleasing measure or has it a deeper need later?

Both. It has importance when you want to match data from different projects. Data in project with different reference point will be shifted. This is affecting not only import, but also templates.
An example of practical use: When I have an existing map and creating new map in neighbouring terrain, I just rewrite the values of reference point (the rounded number is better remembered) and declination from existing map into new project. Then, the maps will be easily connected.