Plot array of geolocated data on a world map?

Questions
1

I’m trying to overlay LEO sensor data on maps from GeoGraphics. The data is an array of radiances (~ 6K x 6K) which has been geolocated, i.e. each point in the array has an associated lat/lon.

Is it possible to create a geographic entity out of the LEO data and location, and give that to GeoGraphics? Or is there a better approach?

I think I’m looking for something that, if it existed, would be called GeoArrayPlot[].

Thank you.

2

Vincent,

You could use GeoRegionValuePlot or GeoListPlot. e.g.

data = {{28.3861, -81.4824, 11.}, {28.3861, -81.4825, 6.}, {28.386, -81.4826, 16.},
{28.3859, -81.4829, 32.}, {28.3858, -81.4832, 43.}, {28.3857, -81.4837, 51.},
{28.3856, -81.4841, 54.}, {28.3855, -81.4846, 54.},{28.3853, -81.4849, 45.},
{28.3852, -81.485, 17.},{28.3852, -81.4849, 16.}, {28.3853, -81.4847, 28.},
{28.3854, -81.4843, 45.}, {28.3855, -81.4838, 56.},{28.3857, -81.4833, 64.},
{28.3858, -81.4827, 72.},{28.386, -81.4821, 78.}, {28.3862, -81.4814, 82.},
{28.3864, -81.4807, 83.}, {28.3866, -81.48, 83.},{28.3868, -81.4793, 85.}};

GeoRegionValuePlot[GeoPosition@*Most@# -> Last@# & /@ data,
 GeoBackground -> "StreetMap",
 GeoProjection -> "Mercator"]

5398plot.png
5398plot.png594×292 41.9 KB

GeoListPlot[
 Style @@@ 
  Transpose[{GeoPosition /@ data[[All, ;; 2]], 
    ColorData["Rainbow"] /@ Rescale[data[[All, -1]]]}], 
 GeoBackground -> "StreetMap", GeoProjection -> "Mercator"]

1840plot.png
1840plot.png525×249 38.8 KB

3

Thank you Rohit. Your suggestions produce some interesting results. However, I find that I have to significantly decimate my data, otherwise neither function returns. Unfortunately, this obscures the nature of the imagery.

I notice GeoStyling[“Satellite”] returns an Image[] with geographical metadata. The metadata specifies a lat/lon region. I wonder if an array of positions can be shoehorned into that.

4

I have run into the same issue when dealing with a large number of points. Filtering using GeoWithinQ is slow because it hits Wolfram’s servers and will also fail for a large number of points. Filtering using GeoGridRange is also very slow. Outline of a workaround that I use.

geoPositions = RandomGeoPosition[Entity["Country", "UnitedStates"], 1000];

positions = geoPositions /. GeoPosition[p_] -> p; (* Extract coordinates *)

bounds = CoordinateBounds[positions]; (* Bounding box *)

(* Divide bounding box *)
lats = FindDivisions[First@bounds, 6];
longs = FindDivisions[Last@bounds, 6];

(* Subdivided bounding boxes *)    
grid = Table[{i, j}, {i, lats}, {j, longs}]; 

(* Rectangle for one subdivision *)
section = Rectangle[{35, -110}, {40, -100}];

(* Select positions in the rectangle *)    
selected = GeoPosition@Select[positions, RegionMember[section, #] &]

GeoListPlot[selected, 
 GeoBackground -> GeoStyling["SatelliteWithLabels"], GeoServer -> "DigitalGlobe"]

3049plot.jpg
3049plot.jpg525×334 81.5 KB

5

Alas, I really need to overlay an image (again, with a corresponding array of geopositions), such as this…

VIIRS-I5.jpg
VIIRS-I5.jpg474×473 97 KB

6

You never mentioned that requirement. As long as you know the geo bounding box of the image, use the method in my previous reply to select the points within that rectangle and then

image = Import["~/Downloads/VIIRS-I5.png"];
GeoListPlot[selected, GeoBackground -> GeoStyling[{"Image", image}]]

10948plot.jpg
10948plot.jpg525×335 76.5 KB

7

I’m not being clear.

It’s the other way around. I want to draw the VIIRS image on a GeoGraphics object, according to the lat/lon array for the VIIRS pixels.