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I am trying to create a map using tm_shape on r

While the process is relatively easy with regular .tif rasters the process seems more complicated when I try to use a raster from a digitized historic map to be the background (historic.tif).

When I load the historic.tif file on QGIS I can then plot my other shapefiles (roads, cities) and make the map. However on r I can't load the file. I get the following message :

This historic.tif is an old map of Liberia that I found in the archives and digitized using QGIS and then saved as a .tif file.

Error in .local(.Object, ...) :

Error in .rasterObjectFromFile(x, band = band, objecttype = "RasterLayer", : Cannot create a RasterLayer object from this file. (file does not exist)

library(sf)
library(raster)
library(dplyr)
library(spData)
library(spDataLarge)
library(rgdal)
library(rgeos)

library(tmap)

historic_map <- raster("~/historic.tif")

Does anyone has a solution to propose?

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7
  • "File does not exist" makes me think the file does not exist. What does file.exists("~/historic.tif") say?
    – Spacedman
    Sep 25, 2019 at 11:52
  • Hi @Spacedman it says [1] TRUE
    – Marcel Campion
    Sep 25, 2019 at 11:54
  • Can you load any TIF files? Is this one corrupt? What does file.info("~/historic.tif") say?
    – Spacedman
    Sep 25, 2019 at 12:02
  • Yes I can load other raster tif files.
    – Marcel Campion
    Sep 25, 2019 at 12:25
  • Can you share this tif file somewhere? Otherwise I think we're stuck...
    – Spacedman
    Sep 25, 2019 at 12:47

1 Answer 1

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There seems to be nothing wrong with the file and I can't reproduce the error except by trying to access a file that doesn't exist. I have the file in the same folder that I start R from (ie ./) and get this:

> file.size("./liberia_concessions.tif")
[1] 7747782

> lc = raster::raster("./liberia_concessions.tif")
> lc
class      : RasterLayer 
band       : 1  (of  4  bands)
dimensions : 1117, 1732, 1934644  (nrow, ncol, ncell)
resolution : 0.00450692, 0.00450692  (x, y)
extent     : -13.00627, -5.200282, 3.311637, 8.345867  (xmin, xmax, ymin, ymax)
crs        : NA 
source     : /nobackup/rowlings/Downloads/liberia_concessions.tif 
names      : liberia_concessions 
values     : 0, 255  (min, max)

and then:

> library(raster)
Loading required package: sp
> lcs = stack("./liberia_concessions.tif")
> plotRGB(lcs)
Warning message:
In couldBeLonLat(x) : CRS is NA. Assuming it is longitude/latitude

enter image description here

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6
  • do you know the equivalent of plotRGB(lcs) with tm_shape so I keep the original colors of the map. When I run map= tm_shape(lcs) + tm_raster() I get the map with colors from light orange to red however I would like to keep the original colors. I guess it has something to with the bands.
    – Marcel Campion
    Sep 26, 2019 at 10:06
  • So is it not giving "File not found" errors now? What did you change? We need to answer the question of why you were getting "File not found" even though R said the file exists.
    – Spacedman
    Sep 26, 2019 at 11:49
  • Asking how to show a three-band raster in tmap is a new question (and you can answer this yourself by reading the help for tm_raster).
    – Spacedman
    Sep 26, 2019 at 11:50
  • So what works best is to import the raster file as lcs = brick("~path/liberia_concessions.tif"). Then change the crs crs(lcs) <- "+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0"
    – Marcel Campion
    Sep 27, 2019 at 12:32
  • Finally to plot the map respecting the original colors I did map = tm_shape(lcs) + tm_rgb() . It is as simple as that.
    – Marcel Campion
    Sep 27, 2019 at 12:33

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