Easier offline basemap creation

Ideas
1

Hi all,

Re-entering the ODK suite after years, I am testing features and capabilities (so far very happy with the potentials of this tool). This testing also generates ideas. For example the offline basemap creation. We work with hundreds of enumerators and numerous Area of Interest (AOI's) and I estimate that this current process of offline basemap creation could be a delicate (error prone) one.

Ideally, an ODK-central project stores 1 (or more) global datasets. With one push on a button (main menu) the enumerator sees this global dataset and can select an AOI (preferably with an entity geometry layer plotted on top so that he/she can easily detect where he/she will be going to). Then, (with a maximum AOI size, defined by the ODK app, in order not to story too many data) he/she can select the AOI and download it straight away to their phone.

I heard licensing for global datasets is an issue, but I know that for example Landsat data is free of use and has global coverage. And there might be more global datasets that can be used freely.

Anyway, this is my ideal situation. With 50+ project areas and hundreds of enumerators it is quite some work to create offline MTB-maps for our enumerators and -like I said- I also see potential problems arise downloading MTB files from a location where the enumerators have to login to.

Thanks!

Kind regards,

Edmond

2

Couple of questions for you, @Edmonds.

  1. How exactly are the AOIs being used and what level of detail would you need? If it's just to detect where they are going, you could have a geofence question that only lets them proceed if they are in their assigned AOI, no?
  2. Are your enumerators well-trained enough to always select the correct AOI? Or would it be something you'd prefer to specify in the form design (or an entity list)?
  3. Do the basemaps need to be satellite raster tiles (like these) or could they be vector tiles like these? Vectors are much smaller in size (100 GB for planet vs 3 TB).
3

Hi Yaw,

  1. For us we would preferable need parcel level, where you can distinguish parcel boundaries in rural areas. I did some tests in QGIS and a Maximum Zoom Level of 17 seems to suffice. It is basically to help enumerators to map planting sites, so the basemap should help them to see if the polygon they mapped makes sense. Geofencing is not what we would use here since we do not want to frustrate the field work.

  2. No. A map with entities (registered polygons) can help them to locate their planting sites and should enable them to select the AOI(s) around those polygons for downloading map tiles. An elegant solution would be to create a standard AOI (vector window) tile (to limit the size of a tile download) that you can move around a world basemap and download the data for that specific AOI.

  3. Preferably satellite since this helps them to locate parcel boundaries (see answer 1). I created a tile from Google Satellite data (maximum zoom level 17) of 100MB and this seemed to work fine.

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