Map content for the Uni HD App

Requirements

• gdal, also available to install via brew install gdal

Resources

• Lagekarten der Uni Heidelberg: http://www.uni-heidelberg.de/universitaet/besucher/karten/

Generating Tiles

1. Create VRT file from map image with at least 4 sets of coordinates (x,y) in pixels from the top left and (lat, long) in degrees:

   $ gdal_translate -of VRT -a_srs EPSG:4326 [-gcp x y long lat]* [source_file] [destination_file]

2. Generate tiles:

   $ python gdal2tiles.py -p mercator [vrt_file] -z 15-20

Coordinates

• INF: -gcp 510 543 8.658369 49.422397 -gcp 2920 489 8.674420 49.422641 -gcp 3237 2805 8.676662 49.412631 -gcp 1482 2266 8.664986 49.414950
• ALT: -gcp 5331 1875 8.716172 49.410304 -gcp 2915 2136 8.705491 49.409538 -gcp 94 1482 8.693046 49.411565 -gcp 3835 753 8.709578 49.413607
• BERG: -gcp 537 1353 8.682831 49.408787 -gcp 3384 2434 8.687846 49.408416 -gcp 6474 1567 8.692385 49.410241 -gcp 3391 710 8.687073 49.410302

Deployment

• Upload to server directory /static/map-tiles/{campusRegion.identifier}/

Displaying on iOS

• Add a MKTileOverlay with appropriate URL template to the map view:

   MKTileOverlay *overlay = [[MKTileOverlay alloc] initWithURLTemplate:[NSString stringWithFormat:@"%@/{z}/{x}/{y}.png", serverURL]];
   overlay.geometryFlipped = YES;
   overlay.minimumZ = 14;
   overlay.maximumZ = 17;
   overlay.canReplaceMapContent = NO;
   [mapView addOverlay:overlay level:MKOverlayLevelAboveLabels];
  

• In mapView:rendererForOverlay: return an MKTileOverlayRenderer initialized with the tile overlay