# 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 or `Plasio`_.

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.

## 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.

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 options 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, eg: “POLYGON((0 0, 5000 10000, 10000 0, 0 0))”. This option can be specified more than once by placing values in an array.

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.

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 takes the looks like the following:

      {
          "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, structured as a JSON object of key/value string pairs.

query

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