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I'm working with Corine Land Cover Accounting Layers files called "CLC2018ACC_V2018_20.tif.ovr" and "CLC2000ACC_V2018_20.tif.ovr". My goal is to get both qualitative and quantitative informations on the expansion of the forest cover in europe to propose those areas (where the forest is naturally coming back) as a potential object for passive rewilding project. I imported the first file in this way:

clc00 <- raster("CLC2000ACC_V2018_20.tif.ovr")

and then I plotted it with:`

plot(clc00)

the output is a map of Europe with values between 0 and more than 8000. How can I extract only the forest values? These should be the codes of the different land cover types: https://image.discomap.eea.europa.eu/arcgis/rest/services/Corine/CLC1990_WM/MapServer/legend

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  • When I get downloads from the Copernicus Land Monitoring Service the filenames all start like "U2006_CLC2000_V2020_20u1" which is similar but not the same as yours, but my data range is 0 to 255 which ties with the land cover class values. land.copernicus.eu/pan-european/corine-land-cover pick a year, see map, click "Download" get zip, unzip to get another zip, unzip to get DATA,Documents,Legend,Metadata folders. Are we on the same data?
    – Spacedman
    Jan 4, 2022 at 16:25
  • eea.europa.eu/data-and-maps/data/…, here you have my data. I downloaded "CLC2000 Accounting Layer " file and "CLC2018 Accounting Layer" file. Jan 4, 2022 at 16:26
  • I noticed the same thing too. I don't know why the Corine Land Cover Accounting Layers files have different values range! Anyway, these are the right data to use if you want to compare CLC Changes between non-consecutive inventories as the user manual states: land.copernicus.eu/user-corner/technical-library/…. Jan 4, 2022 at 16:32

1 Answer 1

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This:

clc00 <- raster("CLC2000ACC_V2018_20.tif.ovr")

is reading the overlay file. You don't want to do that. Read the tif:

> clc = raster("./CLC2000ACC_V2018_20.tif")
Warning message:
In showSRID(SRS_string, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded datum European Terrestrial Reference System 1989 in Proj4 definition
> clc
class      : RasterLayer 
dimensions : 46000, 65000, 2.99e+09  (nrow, ncol, ncell)
resolution : 100, 100  (x, y)
extent     : 9e+05, 7400000, 9e+05, 5500000  (xmin, xmax, ymin, ymax)
crs        : +proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +units=m +no_defs 
source     : CLC2000ACC_V2018_20.tif 
names      : CLC2000ACC_V2018_20 
values     : 111, 999  (min, max)
attributes :
        ID  COUNT CLC_CODE              LABEL1       LABEL2
 from: 111 777883      111 Artificial surfaces Urban fabric
  to : 999  40471      999        999 (Nodata) 999 (Nodata)
                  LABEL3   R   G   B      RED GREEN     BLUE
 Continuous urban fabric 230   0  77 0.901961     0 0.301961
            999 (Nodata) 255 255 255 1.000000     1 1.000000

These values are from 111 to 999 and correspond to the land classes.

You can get the value metadata using levels:

> levels(clc)
[[1]]
    ID     COUNT CLC_CODE                        LABEL1
1  111    777883      111           Artificial surfaces
2  112  16528943      112           Artificial surfaces
3  121   2782230      121           Artificial surfaces
[etc etc etc]

The raster package isn't brilliant for categorical raster data, so you might consider switching to the terra package, which might be better? Not sure...

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  • Thank you very much! Now I'm trying to list the two files from 2000 and 2018 in this way: rlist <- list.files(pattern="") but I don't know what to put inside the quotation marks. If I'd manage to do it then my idea would be: import <- lapply(rlist,raster) clc0018 <- stack(import) and finally plot(clc0018). Any guess? thanks a lot. Jan 5, 2022 at 12:04
  • basically my problem is that I don't know which file is the right one to coose.. Jan 5, 2022 at 12:14
  • Read the files that end in .tif - they are the true source of the raster data. The .ovr files are "overviews", basically low-resolution approximations for quick rendering to save software having to load a massive .tif if all you want is a simple view.
    – Spacedman
    Jan 5, 2022 at 13:51
  • Sure, but if I rename the 2 tiff file in order to have a common part like "aaaCLC2000ACC_V2018_20" and "aaaCLC2018ACC_V2018_20" and then rlist <- list.files(pattern="aaa"); import <- lapply(rlist,raster); import the output is: [[1]] class : RasterLayer values : -32768, 32767 (min, max) [[2]] class : RasterLayer values : -32768, 32767 (min, max). that is, again the wrong values files! Jan 5, 2022 at 15:27
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    yes I do. Should I just ask a new question? Jan 5, 2022 at 15:31

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