Need tips on weighted heatmap from multiple rasters

[1000days]

I'm not a pro yet so I'm here to check this with all of you.

I'm hoping to combine 15 isochrone rasters in QGIS into a heatmap to show overall coverage. Some areas are more important than the others so I want to weight certain rasters higher. Since the pixels are already aligned, I'm thinking zonal stats or some raster math could work, but I'm not sure how to apply those weights when summing. Has anyone done something similar? thanks!

 

[Forgotten_Wealth6]

I'm not a pro yet so I'm here to check this with all of you.

I'm hoping to combine 15 isochrone rasters in QGIS into a heatmap to show overall coverage. Some areas are more important than the others so I want to weight certain rasters higher. Since the pixels are already aligned, I'm thinking zonal stats or some raster math could work, but I'm not sure how to apply those weights when summing. Has anyone done something similar? thanks!

You're on the right track. I once completed a large-scale project similar to this to identify optimal wildlife habitats, and the Raster Calculator in QGIS is your best friend for this exact task. Before you build your expression, are your isochrone rasters simple binary files with values like 1 for coverage and 0 for no coverage?

 

[Meowzilla]

You're on the right track. I once completed a large-scale project similar to this to identify optimal wildlife habitats, and the Raster Calculator in QGIS is your best friend for this exact task. Before you build your expression, are your isochrone rasters simple binary files with values like 1 for coverage and 0 for no coverage?

Here's the basic idea:
("raster1@1" * weight1) + ("raster2@1" * weight2) + ... + ("raster15@1" * weight15)

You'd just put that whole thing into the Raster Calculator in QGIS. Make sure your weight1, weight2, etc., are decimal numbers. The higher the weight, the more that raster will contribute to the final heatmap value.
This is pretty standard practice for creating composite indices or weighted overlay maps.

 

[LayerShift]

I actually did something similar a while back when I was working on mapping out emergency response zones. I used the Raster Calculator to adjust the coverage areas based on priority, it's pretty much the same idea you're working with! It turned out really well once I got the rasters lined up just right. So, trust me, you're definitely headed in the right direction

 

[geoscanpro126]

Great job on the emergency response mapping! The Raster Calculator is ideal for that type of weighted analysis. Making sure those rasters are aligned correctly can be the toughest part, but it seems like you handled it perfectly.