4
votes
2answers
109 views

How to speed up a query for nearest linestring to point data

I have processed a Strahler stream order layer with a lot of river linestrings (type: Multilinestring) and their corresponding strahler number (see information here). Besides I have a point layer. I ...
4
votes
1answer
53 views

How to find closest point without crossing obstacles?

I have a set of points and I'd like to be able to find the nearest point from another layer. The problem is that I need to find the closest point without crossing an obstacle (such as a river, ...
0
votes
0answers
46 views

Assuming nearest point for a region

I'm mapping agricultural cropping systems in Brazil using QGIS. From satellite images I got an raster file with 5136 x 5136 pixels from my field work. Now I need to associate many soil/climate ...
3
votes
1answer
233 views

Estimating cline width at multiple points along a trait gradient

In the map below I have 66 (green) points along the midpoint (0.5) for an allele frequency cline across the region (see map). I created the points by placing a point every 25 km along the 0.5 allele ...