MATLAB's Mapping Toolbox only provides a "geotiffread" function, but it does not have a "geotiffwrite" function (Note). This is the MATLAB program to write a 2D or 3D array to a single or multi-band GeoTIFF file, where data can be either 1-bit monochrome data (i.e. binary or bilevel), 8-bit unsigned integer, 16-bit signed / unsigned integer, 32-bit signed integer, or 32-bit floating point.
Note: Starting from version R2011a, MATLAB also provides its own "geotiffwrite" function (http://www.mathworks.com/help/toolbox/map/rn/bsq4us7-1.html#bsu1ro5-1).
This program is based on GeoTIFF Format Specification under:
It does not need MATLAB's Mapping Toolbox, or any other library.
The motivation to create such a program is because I want to convert the free satelite data from NASA & USGS to the GARMIN 3D topo map for my Garmin GPS receiver. DEM2TOPO (http://people.uleth.ca/~brad.gom/dem2topo) is a wonderful program that can nicely extract contours from the elevation data. However, only 1201x1201 pixels data are supported. For USGS24K DEM data, 1-arc-second SRTM1 data, etc, DEM2TOPO cannot process them directly, which must be converted into GeoTIFF format first (see "Known Issues" in the above site). Although there is a free Windows program "3DEM" that can convert USGS24K DEM & SRTM1 data into GeoTIFF format, sometimes you will still need to interpolate those DEM data for void or missing elevation points.
If you just want to write DEM data to a GeoTIFF file, all you need is a bounding box (2 latitude & 2 longitude) and a 2D or 3D array. Otherwise, you can provide proper GeoTIFF fields to the option argument. To make your life easier, a GUI program “make_option” is also provided. So you can select the proper GeoTIFF fields to generate the option argument. If that’s the case, I recommend that you use "make_option" program to generate option argument instead of constructing it manually.
[option bbox] = make_option([bbox]);
geotiffwrite(filename, bbox, image, [bit_depth, option]);
GeoTIFF file name to be written.
Bounding box with West/East of longitude and South/North of latitude. The latitude & longitude must be in Decimal Degree (DD) format, and they must be in a 2x2 array with the order of:
[ longitude_West, latitude_South;
longitude_East, latitude_North ]
Note: If GTModelTypeGeoKey is not ModelTypeGeographic, bbox will be reset to empty.
2D or 3D array. Although any orientation can be specified through option.Orientation, it is simpler to just use the following default orientation:
First row at North edge; last row at South edge;
First column at West edge; last column at East edge;
Note: By default, "geotiffwrite" assumes intensity image and option.FullColor is 0. So the third dimension of a 3D image represents different bands. If option.FullColor is 1, the third dimension of 3D image must be 3, which indicates R,G,B. i.e. when the third dimension of a 3D array equals to 3, it represents a 3-band GeoTIFF image, unless the option.FullColor is set to 1. When option.ColorMap is set, the specified palette will be used, and you cannot set option.FullColor to 1 at the same time.
(optional) Number of bits to represent a data point (i.e. bits per sample):
1 for 1-bit monochrome data (i.e. binary or bilevel)
8 for 8 bit unsigned integer
16 for 16 bit signed integer
32 for 32 bit floating point (default)
-16 for 16-bit unsigned integer
-32 for 32-bit signed integer
Note: If you set values for option.ColorMap, 16 will be for 16-bit unsigned integer, and you cannot write in 32-bit depth or 1-bit depth. If you set option.FullColor to 1, 8-bit unsigned integer will be used, and you cannot change bit_depth for Full Color image.
(optional) A structure of GeoTIFF fields:
First, please run: [option bbox] = make_option( [bbox] ); This will include most option fields, except the following:
By default, NaN value (void data point) in the image variable will be kept untouched. However, if you decide to replace it with other value (e.g. -32768), you can define it here.
option.FullColor =  | 1
0: Intensity or ColorMap image; (default)
1: FullColor (24-bit RGB) image;
option.ColorMap [Nx3 array]
Where N = 2^bit_depth, and bit_depth can only be 8 or 16. Values in option.ColorMap range from 0 to 65535, and value 0 in image points to the first row in the ColorMap. Columns in option.ColorMap are [R G B]. Black is represented by [0 0 0], and white is represented by [65535 65535 65535].
option.Orientation =  | 2 | 3 | 4 | 5 | 6 | 7 | 8
1: Row from Top, Col from Left; (default)
2: Row from Top, Col from Right;
3: Row from Bottom, Col from Right;
4: Row from Bottom, Col from Left;
5: Row from Left, Col from Top;
6: Row from Right, Col from Top;
7: Row from Right, Col from Bottom;
8: Row from Left, Col from Bottom;
option.ModelTransformationTag [4x4 array]
In most case, ModelPixelScaleTag and ModelTiepointTag from "make_option.m" program is sufficient to transform from raster to model space. If raster image requires rotation or shearing, you can use this ModelTransformationTag to define a 4x4 affine transformation matrix.
- Although not illustrated, it would be easier to use "make_option" for option argument
Data from UTM projected coordinate systems:
img = imread('UTM2GTIF.TIF');
option.GTModelTypeGeoKey = 1;
option.ModelPixelScaleTag = [10;10;0];
option.ModelTiepointTag = [0;0;0;444650;4640510;0];
option.GeogEllipsoidGeoKey = 7008;
option.ProjectedCSTypeGeoKey = 26716;
option.GTCitationGeoKey = 'UTM Zone 16N NAD27"';
option.GeogCitationGeoKey = 'Clarke, 1866 by Default';
Data from colormap indexed scan image:
[img cmap] = imread('o41078a5.tif');
option.GTModelTypeGeoKey = 1;
option.ModelPixelScaleTag = [2.4384;2.4384;0];
option.ModelTiepointTag = [0;0;0;698753.304798;4556059.506392;0];
option.ProjectedCSTypeGeoKey = 32617;
option.PCSCitationGeoKey = 'UTM Zone 17 N with WGS84';
option.ColorMap = 65535*cmap;
img = imread('mlatlon.tif');
option.GeographicTypeGeoKey = 4267;
option.GTCitationGeoKey = 'Geographic Model/GeoTIFF 1.0';
option.GeogCitationGeoKey = 'NAD 27 Datum';
srtm = load_srtm('N46W082.hgt');
6-band GeoTIFF data is available under:
1. 3D array is supported to write Multi-band GeoTIFF data.
2. “make_option” program is created to provide a GUI window to generate option argument for “geotiffwrite” program.
Please download “geotiffwrite” and “make_option” proggrams under:
Please kindly provide your feedbacks, ratings, or comments under: