Tree Density Calculator API¶

Source code: https://bitbucket.org/kul-reseco/localmaxfilter/src.

For issues, bugs, proposals or remarks, visit the issue tracker.

Core¶

———————————————————————————————————————-
Date                : August 2018
Copyright           : © 2018 - 2020 by Tinne Cahy (Geo Solutions) and Ann Crabbé (KU Leuven)
Email               : acrabbe.foss@gmail.com
Acknowledgements    : Translated from Local Maximum Filter [C++ software]
Ghent University, Laboratory of Forest Management and Spatial Information Techniques
Lieven P.C. Verbeke

This file is part of the QGIS Tree Density Calculator plugin and treedensitycalculator python package.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation, either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License (COPYING.txt). If not see www.gnu.org/licenses.
———————————————————————————————————————-

class localmaxfilter.core.local_max_filter.LocalMaxFilter(window_length)[source]¶

Bases: object

A window is used to slide over an image and look for maximum reflectance values in the center of that window.

execute(image_array, area_of_interest=None, snap=None, geo_transform=None, set_progress: callable = None)[source]¶

The function will return an image containing the reflectance values of the local max of a sliding window going over the input image. It is possible to include an area of interest

Parameters:	image_array (ndarray) – 2D Numpy array image area_of_interest (ndarray) – 2D Numpy array image indicating with 0 and 1 the area of interest snap – defines the snap distance geo_transform – contains the pixel size of the raster set_progress – communicate progress (refer to the progress bar in case of GUI; otherwise print to console)
Returns:	dict: Dictionary containing the reflectance values of the local max together with pixel locations

localmaxfilter.core.local_max_filter.printProgress(value: int)[source]¶: Replacement for the GUI progress bar

Interfaces¶

———————————————————————————————————————-
Date                : March 2019
Copyright           : © 2019 - 2020 by Tinne Cahy (Geo Solutions) and Ann Crabbé (KU Leuven)
Email               : acrabbe.foss@gmail.com
Acknowledgements    : Translated from Local Maximum Filter [C++ software]
Ghent University, Laboratory of Forest Management and Spatial Information Techniques
Lieven P.C. Verbeke

This file is part of the QGIS Tree Density Calculator plugin and treedensitycalculator python package.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation, either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License (COPYING.txt). If not see www.gnu.org/licenses.
———————————————————————————————————————-

localmaxfilter.interfaces.run_algorithm_local_max_filter(image_path, window, log_function=<built-in function print>, update_progress_bar=None, mask_path=None, output_base_path=None, snap_distance=None, voronoi=None, feedback=None, context=None)[source]¶

General interface between the GUI/CLI and script.

Parameters:

image_path – the absolute path to the raster file
window – window size in meters
update_progress_bar – function to update the progress bar
log_function – function to log
mask_path – absolute path to the vector file (optional)
output_base_path – base path for output files (optional)
snap_distance – snap distance for output points (optional)
voronoi – set to True if you want voronoi polygons as output (optional)
feedback – necessary for the processing tool
context – necessary for the processing tool

Returns:

———————————————————————————————————————-
Date                : August 2018
Copyright           : © 2018 - 2020 by Tinne Cahy (Geo Solutions) and Ann Crabbé (KU Leuven)
Email               : acrabbe.foss@gmail.com

This file is part of the QGIS Tree Density Calculator plugin and treedensitycalculator python package.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation, either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License (COPYING.txt). If not see www.gnu.org/licenses.
———————————————————————————————————————-

localmaxfilter.interfaces.imports.check_path(path)[source]¶

Check if path exists. Skipp path which are in memory

Parameters:	path – the absolute path to the input file

localmaxfilter.interfaces.imports.import_image(image_path, mask_path=None, window_size=None, reflectance=False, feedback=None, context=None)[source]¶

Get an input image as array from file path. If a vector layer path is given, the raster is clipped, using a 2*window_size buffer. Also return the the spatial reference system and the geo_transform.

Parameters:	image_path – the absolute path to the input image mask_path – the absolute path to the polygon file window_size – the size of the sliding window, only required if mask is given reflectance – return reflectance values instead of DN between 0 and 255 feedback – necessary for the processing tool context – necessary for the processing tool
Returns:	numpy array [#bands x #rows x #columns], ogr srs and geo_transform

localmaxfilter.interfaces.imports.import_vector_as_image(path, geo_transform, image_size, image_srs, window_size, feedback=None, context=None)[source]¶

Browse for a vector file and return it as a raster after buffering with window_size.

Parameters:	path – the absolute path to the vector file geo_transform – 6 geo transformation coefficients image_size – size of the image image_srs – OSR spatial reference system object window_size – the size of the sliding window feedback – necessary for the processing tool context – necessary for the processing tool
Returns:	numpy array

———————————————————————————————————————-
Date                : August 2018
Copyright           : © 2018 - 2020 by Tinne Cahy (Geo Solutions) and Ann Crabbé (KU Leuven)
Email               : acrabbe.foss@gmail.com

This file is part of the QGIS Tree Density Calculator plugin and treedensitycalculator python package.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation, either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License (COPYING.txt). If not see www.gnu.org/licenses.
———————————————————————————————————————-

localmaxfilter.interfaces.exports.check_path(path)[source]¶

Check if path exists. Skipp path which are in memory

Parameters:	path – the absolute path to the input file

localmaxfilter.interfaces.exports.write_mask_layer(output_path, mask_path, trees_path, log=<built-in function print>)[source]¶

Copy the input mask to a new shapefile, and add an extra attributes:

field ‘Area_ha’ contains the area of the polygon
field ‘TreeCount’ contains the number of trees found in that polygon
field ‘TreeDens’ contains the number of trees per ha

Parameters:	output_path – the absolute path to the output Shapefile mask_path – the absolute path to the input vector file trees_path – the absolute path to the input point vector file log – log function

localmaxfilter.interfaces.exports.write_point_layer(output_path, points_dict, geo_transform, srs, mask_path=None, feedback=None, context=None)[source]¶

Convert the input point dictionary to a vector point layer using the image metadata (srs and geo_transform).: The points are clipped to fit the given mask. https://gis.stackexchange.com/questions/268395/converting-raster-tif-to-point-shapefile-using-python

Parameters:

output_path – the absolute path to the output vector file
points_dict – a dictionary containing the raster values and pixel locations Keys: RasterVal, Pixel with keys x and y
mask_path – the absolute path to the mask file for clipping
geo_transform – geo transformation coefficients
srs – spatial reference system
feedback – necessary for the processing tool
context – necessary for the processing tool

localmaxfilter.interfaces.exports.write_voronoi_layer(output_path, point_path, mask_path=None, feedback=None, context=None)[source]¶

Convert the input point vector to a Voronoi polygon layer and clip it by the mask layer

Parameters:	output_path – the absolute path to the output voronoi vector file point_path – the absolute path to the input point vector file mask_path – the absolute path to the overlay vector file feedback – necessary for the processing tool context – necessary for the processing tool

———————————————————————————————————————-
Date                : August 2018
Copyright           : © 2018 - 2020 by Tinne Cahy (Geo Solutions) and Ann Crabbé (KU Leuven)
Email               : acrabbe.foss@gmail.com
Acknowledgements    : Translated from Local Maximum Filter [C++ software]
Ghent University, Laboratory of Forest Management and Spatial Information Techniques
Lieven P.C. Verbeke

This file is part of the QGIS Tree Density Calculator plugin and treedensitycalculator python package.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation, either version 3 of the License, or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License (COPYING.txt). If not see www.gnu.org/licenses.
———————————————————————————————————————-

CLI¶

A window is used to slide over an image and look for maximum reflectance values in the center of that window.

usage: treedensity [-h] [-m ] [-v] [-s ] [-o ] image sliding_window

Positional Arguments¶

`image`	input reflectance image path
`sliding_window`	length of the sliding window, in meters (default 5 m), should be a multiple of the image pixel size

Named Arguments¶

`-m, --mask`	overlapping vector mask path
`-v, --voronoi`	create a Voronoi shapefile based on the tree locations (default off) Default: False
`-s, --snap`	give distance [m] for the snap tool, should be max half of the window size, tree tops which are closer to each other than the given distance will be taken as one
`-o, --output`	path for output files, give base without extension (default: in same folder with extension _window_{}.shp)