matlab geotiff,(Not recommended) Read GeoTIFF file[通俗易懂]

geotiffread

(Not recommended) Read GeoTIFF file

geotiffread is not recommended, except when reading a GeoTIFF

file from a URL or when reading multiple images from the same file. In other situations,

use readgeoraster instead. For more information, see Compatibility Considerations.

Description

[A,R] = geotiffread(filename)

reads a georeferenced grayscale, RGB, or multispectral image or data grid from the

GeoTIFF file specified by filename into A

and creates a spatial referencing object, R.

[X,cmap,R]

= geotiffread(filename)

reads an indexed image into X and the associated colormap into

cmap, and creates a spatial referencing object,

R.

[A,refmat,bbox]

= geotiffread(filename)

reads a georeferenced grayscale, RGB, or multispectral image or data grid into

A, the corresponding referencing matrix into

refmat, and the bounding box into bbox.

X, the associated colormap into

cmap, the referencing matrix into

refmat, and the bounding box into

bbox. The referencing matrix must be unambiguously defined by

the GeoTIFF file, otherwise it and the bounding box are returned empty.

[___] = geotiffread(url)

reads the GeoTIFF image from a URL.

[___] = geotiffread(___,idx)

reads one image from a multi-image GeoTIFF file or URL.

Examples

Read and Display the Boston GeoTIFF Image

[boston,R] = geotiffread(‘boston.tif’);

figure

mapshow(boston,R);

axis image off

boston.tif copyright © GeoEye™, all rights reserved.

Input Arguments

filename — Name of GeoTIFF file

character vector | string scalar

Name of the GeoTIFF file, specified as a string scalar or character

vector. Include the folder name in filename or place the

file in the current folder or in a folder on the MATLAB® path. If the named file includes the extension

.TIF or .TIFF (either upper- or

lowercase), you can omit the extension from

filename.

idx — Index of image in GeoTIFF file

1 (default) | positive integer

Index of image in GeoTIFF file, specified as a positive integer. For

example, if idx is 3,

geotiffread reads the third image in the file. By

default, idx indexes to the first image in the

file.

url — Internet URL

character vector | scalar string

Internet URL, specified as a string scalar or character vector. The URL

must include the protocol type (e.g., “https://”).

Output Arguments

A — Georeferenced image or data grid

M-by-N numeric matrix | M-by-N-by-P

numeric array

Georeferenced image or data grid, returned as one of the following:

An M-by-N numeric matrix

when the file contains a grayscale image or data grid

An

M-by-N-by-P

numeric array when the file contains a color image,

multispectral image, hyperspectral image, or data grid

The class of A depends on the storage class of the

pixel data in the file, which is related to the

BitsPerSample property as returned by the imfinfo function.

R — Spatial referencing object

geographic raster reference object | map raster reference object

Spatial referencing object, returned as one of the following.

A geographic raster reference object of type GeographicCellsReference or GeographicPostingsReference. This object is

returned when the image or data grid is referenced to a

geographic coordinate system.

A map raster reference object of type MapCellsReference or

MapPostingsReference. This object is returned when the

image or data grid is referenced to a projected coordinate

system.

X — Indexed image

M-by-N numeric matrix

Indexed image, returned as an M-by-N

numeric matrix.

cmap — Color map

c-by-3 numeric matrix

Color map associated with indexed image X, specified

as an c-by-3 numeric matrix. There are

c colors in the color map, each represented by a red,

green, and blue pixel value. Colormap values are rescaled into the range

[0,1].

refmat — Referencing matrix

3-by-2 numeric matrix | []

Referencing matrix, returned as 3-by-2 numeric matrix that transforms

raster row and column indices to or from geographic coordinates according

to:

[lon lat] = [row col 1] * refmat

refmat defines a (non-rotational, non-skewed)

relationship in which each column of the data grid falls along a meridian

and each row falls along a parallel. refmat must be

unambiguously defined by the GeoTIFF file, otherwise it and the bounding

box, bbox, are returned empty.

Data Types:double

bbox — Bounding box

2-by-2 numeric matrix | []

Bounding box, returned as a 2-by-2 numeric matrix that specifies the

minimum (row 1) and maximum (row 2) values for each dimension of the image

data in the GeoTIFF file. bbox is returned empty if

refmat is ambiguously defined by the GeoTIFF

file.

Data Types:double

Tips

geotiffread imports pixel data using the TIFF-reading

capabilities of the MATLAB function imread and likewise shares any

limitations of imread. Consult the imread

documentation for information on TIFF image support.

Compatibility Considerations

geotiffread is not recommended

Not recommended starting in R2020a

geotiffread is not recommended, except when reading a GeoTIFF

file from a URL or when reading multiple images from the same file. In other

situations, use readgeoraster instead. There are no plans to remove

geotiffread.

Unlike geotiffread, which returns a referencing matrix in

some cases, the readgeoraster function returns a raster

reference object. Reference objects have several advantages over referencing matrices.

Unlike referencing matrices, reference objects have properties that

document the size of the associated raster, its limits, and the

direction of its rows and columns. For examples of reference object

properties, see GeographicCellsReference and

MapPostingsReference.

You can manipulate the limits of rasters associated with reference

objects using the geocrop or mapcrop functions.

You can manipulate the size and resolution of rasters associated with

reference objects using the georesize or mapresize functions.

This table shows some typical usages of geotiffread and how

to update your code to use readgeoraster instead. Unlike

geotiffread, the readgeoraster

function requires you to specify a file extension. For example, use [Z,R] =

readgeoraster(‘boston.tif’).

Not RecommendedRecommended[A,R] = geotiffread(filename);[A,R] = readgeoraster(filename);

[X,cmap,R] = geotiffread(filename);[X,R,cmap] = readgeoraster(filename);

[A,refmat,bbox] = geotiffread(filename);[A,R] = readgeoraster(filename);

xlimits = R.XWorldLimits;

ylimits = R.YWorldLimits;

bbox = [xlimits’ ylimits’];

Introduced before R2006a