geojson.io | simple tool for creating , viewing , and sharing spatial data | Map library

I am looking for a way to create a geojson file from the distributions of the health sectors in my region which are different than any political division readily available on osm:

There are fantastic tools such as geojson.io to draw custom polygons but because of the complexity I would need a tool that allows me to overlay an image to use it as a template or that does this automatically. If this makes a difference, I may be able to extract the silhouette with any computer vision library but my problem of how to get from an image or shape to geojson still remains.

Which is the fastest way to approach this?

I tried this example and it worked as shown in the link: GeoJSON issues with Plotly choropleth_mapbox.

Now I'm trying to use it in my Flask app without success and without any error message.

I prepared an example about what I'm doing:

i would like to know why the below posted geojson format is invalid. i tried to visualize its data in http://geojson.io

but nothing gets displayed.

geojson

I'm doing some mapping of coordinates to a geojson file using shapely, but it seems that the mapping is wrong. In the image below (from geojson.io) you see the polygon and in yellow the point I want to map. In this case shapely tell me that the point is inside the polygon, but as you see this is false.

My code:

I want to find the area in square metre for a polygon created from latitude and longitude.

Using the NetTopology in C# I'm getting a 'found non-noded intersection' Exception when determining the difference between two specific geometries.

These geometries are the result of using several routines like CascadedPolygonUnion.Union, Intersection, and Difference.

At some point, we have a MultiPolygon from which we want to cut out another geometry (Polygon):

We use this code to try and cut off the 'red' polygon:

I have a map editor that lets the user draw and modify polygons. Polygons can be drawn inside polygons to create "holes."

The problem I am facing is after drawing inside polygon's on the map and saving the map data--the map becomes mangled on page refresh. The map does not show the original shape even though the GeoJSON is correct. I suspect the addfeature event is not handling inner and outer polygon's properly.

How can I fix addfeature to properly display the saved map data?

Expected output:

Actual output:

Update: I have tried this and it partially works but it cuts polygon data off. I added another layer to see the original shape:

I am trying to create a visualisation in Altair that overlays major rivers onto a map of Europe, and some of the surrounding countries. I used this website to download a custom GeoJSON file of Europe, Asia and Africa. I then managed to successfully plot the base map using GeoPandas (imported as gpd) in the following code:

I want to get the minimum set of polygons that provide the maximum coverage. For example, for the polygons in the image below, the ones in red should not make the cut as they are already covered by one or more polygons (getting rid of the polygons within other polygons is not enough). Holes are ok and expected (as in the second image).

The data for the polygons above is here:

http://geojson.io/#id=gist:rumicuna/b36cab7d0019511b92120db130a73d44&map=8/38.311/-81.403

I would happily take an algorithm in any language or even a mathematical description on how to approach this problem. The image is an example, but in my case, I have thousands of polygons (satellite image bounds).