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ImageOverlay behaviour with WG84 rasters

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#2,054 2 comments 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript, python

Research direction

Start by reproducing the supplied TIFF example with rasterio and folium.ImageOverlay, then compare its EPSG:4326 handling with the EPSG:3857 QGIS result. Read the ImageOverlay projection and bounds behavior alongside Leaflet's image-overlay expectations; done means the discrepancy is explained and the issue's expected rendering or limitation is documented.

Written by the indexing model from the issue text.

Description

I have a non-expected result when using this code (the raster used is attached to this message):

raster_path = '2019-06-15.tiff'
with rasterio.open(raster_path) as src:
    raster_data = src.read(1)
    bounds = src.bounds
    
m = folium.Map(location=[(bounds.top + bounds.bottom) / 2, (bounds.left + bounds.right) / 2], zoom_start=10)

# Create an ImageOverlay
img_overlay = ImageOverlay(
    image=raster_data,
    bounds=[[bounds.bottom, bounds.left], [bounds.top, bounds.right]],
    opacity=0.6,
    interactive=False,
    cross_origin=True,
    zindex=1,
    mercator_project=True
)

# Add the overlay to the map
img_overlay.add_to(m)

m.save('map.html')

Indeed, my result html map presents shapes that are not consistent with the same map I could have just by using QGIS.

For instance the result of this code gives this in a specific region:
image

while using QGIS in an EPSG:3857 projection system gives this:
image

My raster has natively an EPSG:4326 projection system. I suspect the issue comes from how ImageOverlay changes the projection system.

Can anyone reproduce this and explain how I could obtain the same result as in QGIS which is the correct reference for me?

Thanks,
Vivien

2019-06-15.zip

Dominant language
Python
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