Recoding (GWB_REC)#

This module conducts Recoding of categorical class values.

Requirements#

A single band (Geo)TIFF image in data format byte.

Processing parameter options are stored in the file input/rec-parameters.txt.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; GWB_REC parameter file:
;; NOTE: change values only at the end of the file between the lines in *****
;;
;; REC: Recode image classes
;; Input image requirements: classes within the range [0, 255] byte
;; Output: the same image coverage but with recoded class values
;;
;; Please specify recoding values with two entries per line.
;; GWB_REC will error/exit if not in correct range.
;; Class values not found in the image will be skipped.
;; Class values not in the list will not be re-coded.
;; If an old value appears on more than one line, the last one listed is used.
;;
;; Recoding rule:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; The first value is the original value and the second is the new recoded value:
;; original value within [0, 255] byte     new recoded value within [0, 255] byte
;; i.e., to recode class 1 to 12 and class 2 to 22 , enter one line each, like:
;; 1 12
;; 2 22
****************************************************************************
1 120
2 220
****************************************************************************

Example#

The results are stored in the directory output, one directory for each input image accompanied by a log-file providing details on computation time and processing success of each input image.

GWB_REC command and listing of results in the directory output:

$ GWB_REC -i=$HOME/input -o=$HOME/output
IDL 9.1.0 (linux x86_64 m64).
(c) 2024, NV5 Geospatial Solutions, Inc.

GWB_REC using:
dir_input= $HOME/input
dir_output= $HOME/output
% Loaded DLM: TIFF.
Done with: clc3class.tif
Done with: example.tif
Done with: gscinput.tif
Recode finished sucessfully

$ ls -R output/
output/:
clc3class_rec  example_rec  rec.log

output/clc3class_rec:
clc3class_rec.tif

output/example_rec:
example_rec.tif

Remarks#

The recoded images have the suffix _rec.tif to distinguish them from the original images.
To verify the recoding run the command:
```
$ gdalinfo -hist <path2image>
```

Recoding may be useful to quickly setup a forest mask from a land cover map by reassigning specific land cover classes to forest. Please note that most GWB modules require a (pseudo) binary input mask of data type Byte with the assignment:

0 byte: missing data (optional)
1 byte: Background
2 byte: Foreground (i.e., forest)