QGIS 3.10 buffer around polygon in kilometer units

Question

I am trying to make the buffer in kilometers around my polygon.

When I run the "Buffer" option, then I am getting the degrees:

There is quite a few solutions, even similar to mine:

Create buffer in meters?

Understanding QGIS buffer tool units?

How to Change the buffer distance from degrees to meters in QGIS 2.14 Essen?

of which the common denominator is changing the CRS system from WGS to NAD 83. I done it for my layer, which eventually disappeared from the map.#

In terms of this situation, I started looking for the solution, and I found this:

Shapefile disappeared after changing CRS

However, changing the CRS at the project stage didn't resolve my problem:

So even with the best will in the world, having al of the solutions above I cannot make it through. Is there a way to get over this problem and set the buffer in kilometers instead of degrees?

Answer 1

Look at the text at the top of the 3rd image. It says that the layer does not have a projection and will be using the same one as the project CRS.

Since the data shows up nicely when the project CRS is 4326, it is safe to say that the coordinates are not projected (likely in 4326 but could be another CRS). If you simply define its projection and say it is in UTM, the coordinate numbers are not transformed from 4326 to UTM, but are now simply assumed to be in meters instead of degree. A point that was at -100;45 (degrees) is now at -100;45 (meters).

You need to find and set the original projection (4326 or else), then you can reproject the layer to UTM.

Answer 2

You can also export the file, setting the CRS to, for example, EPSG:32631, then you should be able to run the buffer according to m/km/miles/etc on the new shapefile.

Answer 3

Just changing to the right CRS projection. In Indonesia, you can search for UTM Zone 49S --> save feature and reload. Now it will refresh the degrees buffer to meters unit.