1

I am working with two rasters. I am trying to reproject r1 the same way as the raster r2. Rasters are available here

r1

class : RasterLayer dimensions : 30286, 58025, 1757345150 (nrow, ncol, ncell) resolution : 99.99876, 99.99876 (x, y) extent : -2893269, 2909160, 224962.6, 3253525 (xmin, xmax, ymin, ymax) coord. ref. : +proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +datum=NAD83 +units=m +no_defs +ellps=GRS80 +towgs84=0,0,0 values : 0, 7 (min, max)

r2

class : RasterLayer dimensions : 585, 1386, 810810 (nrow, ncol, ncell) resolution : 0.04166599, 0.041666 (x, y) extent : 235.207, 292.9561, 25.04224, 49.41686 (xmin, xmax, ymin, ymax) coord. ref. : +proj=longlat +ellps=WGS84 +no_defs values : -7.904284, 12.21496 (min, max)

I precise that the resolution of r1 is 100 m and the resolution of r2 is supposed to be 4km. Moreover, the system of coordinates is different as one is in degree and another one in meter. I would like to reproject the rasters in order they keep their own resolution and share the same extent.

I did not find a way to do it. When I upload my data in Arcgis, the rasters are aligned as I would like which is not the case with Qgis and R. The final goal would be to allow raster calculations by stacking the raster for example.

I do not want to reproject the raster from r2 to r1 as I am working with thousands of raster that have the same coordinates than r2.

I can work with Arcgis, Qgis, and R. However, I do not know how to code in Python.

Currently, by applying the method by Spacedman (answers below), I obtainedthis figure. This is much better as my rasters are closers but there are still not at the same position when I plot them. Moreover, the resolution of r1 has changed. I am confused to what is the problem.

Improve this question

1 Answer 1

Reset to default
1

The extent of r2 is giving problems because its not in the longitude range -180 to 180, but probably 0 to 360:

extent : 235.207, 292.9561, 25.04224, 49.41686 (xmin, xmax, ymin, ymax)

If you fix that then:

r1p = projectRaster(r1, r2)

will work nicely.

You can fix this by reassigning the extent of a raster to a new extent with the X coordinates minus 360:

> r2 class : RasterLayer dimensions : 585, 1386, 810810 (nrow, ncol, ncell) resolution : 0.04166599, 0.041666 (x, y) extent : 235.207, 292.9561, 25.04225, 49.41686 (xmin, xmax, ymin, ymax) coord. ref. : +proj=longlat +ellps=WGS84 +no_defs data source : in memory names : layer values : 1, 810810 (min, max) > extent(r2) = extent(xmin(r2)-360, xmax(r2)-360, ymin(r2), ymax(r2)) > r2 class : RasterLayer dimensions : 585, 1386, 810810 (nrow, ncol, ncell) resolution : 0.04166602, 0.04166602 (x, y) extent : -124.793, -67.0439, 25.04224, 49.41686 (xmin, xmax, ymin, ymax) coord. ref. : +proj=longlat +ellps=WGS84 +no_defs data source : in memory names : layer values : 1, 810810 (min, max)
Improve this answer
2
  • Thank you for your comments. However, it improves a lot. However, how could I have my rasters like superposed? Currently it improves a lot the reproduction but they are not displayed at the same location. And do you know how I could use projectRaster in a way r1 does not change its spatial resolution (keep it to 100, 100)? Thanks in advance! Commented May 12, 2019 at 21:57
  • You need to create a 100x100 raster that covers the projected extent of the source raster. However I'm not sure I really understand the rest of your comment. Perhaps if you edited your question and included some maps that would improve things. Commented May 12, 2019 at 22:18

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.