pyfor.ground_filter
Classes
Section titled “Classes”Zhang2003
Section titled “Zhang2003”Zhang2003(cell_size, n_windows = 5, dh_max = 2, dh_0 = 1, b = 2, interp_method = 'nearest')Implements Zhang et. al (2003), a progressive morphological ground filter. This filter uses an opening operation combined with progressively larger filtering windows to remove features that are ‘too steep’. This particular implementation interacts only with a raster, so the output resolution will be dictated by the cell_size argument.
Attributes
Section titled “Attributes”| Attribute | Type | Description |
|---|---|---|
n_windows |
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dh_max |
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dh_0 |
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b |
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cell_size |
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interp_method |
Methods
Section titled “Methods”bem(cloud, classified = False, spec = None)Retrieve the bare earth model (BEM). Unlike KrausPfeifer1998, the cell size is defined upon initialization of the filter, and thus it is not required to retrieve the bare earth model from the filter.
| Parameter | Type | Description |
|---|---|---|
cloud |
A Cloud object. | |
classified |
If True, the bare earth model is constructed from the points classified as ground (2). | |
spec |
An optional GridSpec for the model, see Cloud.grid. |
Returns: A Raster object that represents the bare earth model.
normalize
Section titled “normalize”normalize(cloud, classified = False, spec = None)Normalizes the original point cloud in place. This creates a BEM as an intermediate product, please see .bem() to return this directly.
| Parameter | Type | Description |
|---|---|---|
cloud |
The input cloud object to normalize. | |
classified |
If True, the bare earth model is constructed from the points classified as ground (2). | |
spec |
An optional GridSpec for the bare earth model, see Cloud.grid. |
KrausPfeifer1998
Section titled “KrausPfeifer1998”KrausPfeifer1998(cell_size, a = 1, b = 4, g = -2, w = 2.5, iterations = 5, tolerance = 0)Holds functions and data for implementing Kraus and Pfeifer (1998) ground filter. The Kraus and Pfeifer ground filter is a simple filter that uses interpolation of errors and an iteratively constructed surface to filter ground points. This filter is used in FUSION software, and the same default values for the parameters are used in this implementation.
Attributes
Section titled “Attributes”| Attribute | Type | Description |
|---|---|---|
cell_size |
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a |
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b |
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g |
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w |
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iterations |
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tolerance |
Methods
Section titled “Methods”ground_points
Section titled “ground_points”ground_points(cloud)Returns a new Cloud object that only contains the ground points.
Returns:
bem(cloud, cell_size, spec = None)Retrieve the bare earth model (BEM).
| Parameter | Type | Description |
|---|---|---|
cloud |
A cloud object. | |
cell_size |
The cell size of the BEM, this is independent of the cell size used in the intermediate surfaces. | |
spec |
An optional GridSpec for the model, see Cloud.grid. |
Returns: A Raster object that represents the bare earth model.
classify
Section titled “classify”classify(cloud, ground_int = 2)Sets the classification of the original input cloud points to ground (default 2 as per las specification). This performs the adjustment of the input Cloud object in place. Only implemented for .las files. Additionally, the original ground classification is preserved if it exists, so this will only add additional ground points for already classified point clouds.
| Parameter | Type | Description |
|---|---|---|
cloud |
A cloud object. | |
ground_int |
The integer to set classified points to, the default is 2 in the las specification for ground points. |
normalize
Section titled “normalize”normalize(pc, cell_size, spec = None)Normalizes the original point cloud in place. This creates a BEM as an intermediate product, please see .bem() to return this directly.
| Parameter | Type | Description |
|---|---|---|
pc |
A cloud object. | |
cell_size |
The cell_size for the intermediate BEM. Values from 1 to 6 are common. | |
spec |
An optional GridSpec for the model, see Cloud.grid. |