readers.ept

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readers.ept#

Entwine Point Tile (EPT) is a hierarchical octree-based point cloud format suitable for real-time rendering and lossless archival. Entwine is a producer of this format. The EPT Reader supports reading data from the EPT format, including spatially accelerated queries and file reconstruction queries.

Sample EPT datasets of hundreds of billions of points in size may be viewed with Potree.

Default Embedded Stage

This stage is enabled by default

Streamable Stage

This stage supports streaming operations

Example#

This example downloads a small area around the the Statue of Liberty from the New York City data set (4.7 billion points) which can be viewed in its entirety in Potree.

[
   {
      "type": "readers.ept",
      "filename": "http://na.entwine.io/nyc/ept.json",
      "bounds": "([-8242669, -8242529], [4966549, 4966674])"
   },
   "statue-of-liberty.las"
]

Additional attributes created by the EPT addon writer can be referenced with the addon option. Here is an example that overrides the Classification dimension with an addon dimension derived from the original dataset:

[
    {
        "type": "readers.ept",
        "filename": "http://na.entwine.io/autzen/ept.json",
        "addons": { "Classification": "~/entwine/addons/autzen/smrf" }
    },
    {
        "type": "writers.las",
        "filename": "autzen-ept-smrf.las"
    }
]

For more details about addon dimensions and how to produce them, see writers.ept_addon.

Note

The forward option of writers.copc or writers.las cannot work with EPT due to how EPT can mix content and files. There is no single unified metadata value to forward. You will have to explicitly set any output options that you would expect to come from EPT on any writers.

Options#

filename

Path to the EPT resource from which to read, ending with ept.json. For example, /Users/connor/entwine/autzen/ept.json or http://na.entwine.io/autzen/ept.json. [Required]

spatialreference

Spatial reference to apply to the data. Overrides any SRS in the input itself. Can be specified as a WKT, proj.4 or EPSG string. [Default: none]

bounds

The extents of the resource to select in 2 or 3 dimensions, expressed as a string, e.g.: ([xmin, xmax], [ymin, ymax], [zmin, zmax]). If omitted, the entire dataset will be selected. The bounds can be followed by a slash (‘/’) and a spatial reference specification to apply to the bounds.

resolution

A point resolution limit to select, expressed as a grid cell edge length. Units correspond to resource coordinate system units. For example, for a coordinate system expressed in meters, a resolution value of 0.1 will select points up to a ground resolution of 100 points per square meter.

The resulting resolution may not be exactly this value: the minimum possible resolution that is at least as precise as the requested resolution will be selected. Therefore the result may be a bit more precise than requested.

addons

A mapping of assignments of the form DimensionName: AddonPath, which assigns dimensions from the specified paths to the named dimensions. These addon dimensions are created by the EPT addon writer. If the dimension names already exist in the EPT Schema for the given resource, then their values will be overwritten with those from the appropriate addon.

Addons may used to override well-known dimension. For example, an addon assignment of "Classification": "~/addons/autzen/MyGroundDimension/" will override an existing EPT Classification dimension with the custom dimension.

origin

EPT datasets are lossless aggregations of potentially multiple source files. The origin option can be used to select all points from a single source file. This option may be specified as a string or an integral ID.

The string form of this option selects a source file by its original file path. This may be a substring instead of the entire path, but the string must uniquely select only one source file (via substring search). For example, for an EPT dataset created from source files one.las, two.las, and two.bpf, “one” is a sufficient selector, but “two” is not.

The integral form of this option selects a source file by its OriginId dimension, which can be determined from the file’s position in EPT metadata file entwine-files.json.

Note

When using pdal info --summary, using the origin option will cause the resulting bounds to be clipped to those of the selected origin, and the resulting number of points to be an upper bound for this selection.

polygon

The clipping polygon, expressed in a well-known text string, e.g.: POLYGON((0 0, 5000 10000, 10000 0, 0 0)). This option can be specified more than once by placing values in an array, in which case all of them will be unioned together, acting as a single multipolygon. The polygon definition can be followed by a slash (‘/’) and a spatial reference specification to apply to the polygon.

Note

When using pdal info --summary, using the polygon option will cause the resulting bounds to be clipped to the maximal extents of all provided polygons, and the resulting number of points to be an upper bound for this polygon selection.

Note

When both the bounds and polygon options are specified, only the points that fall within both the bounds and the polygon(s) will be returned.

ogr

A JSON object representing an OGR query to fetch polygons to use for filtering. The polygons fetched from the query are treated exactly like those specified in the polygon option. The JSON object is specified as follows:

{
    "drivers": "OGR drivers to use",
    "openoptions": "Options to pass to the OGR open function [optional]",
    "layer": "OGR layer from which to fetch polygons [optional]",
    "sql": "SQL query to use to filter the polygons in the layer [optional]",
    "options":
    {
        "geometry", "WKT or GeoJSON geomtry used to filter query [optional]"
    }
}
requests

Maximum number of simultaneous requests for EPT data. [Minimum: 4] [Default: 15]

header

HTTP headers to forward for remote EPT endpoints, specified as a JSON object of key/value string pairs.

query

HTTP query parameters to forward for remote EPT endpoints, specified as a JSON object of key/value string pairs.

ignore_unreadable

If set to true, ignore errors for missing or unreadable point data nodes.

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