Data Layers

Data layers use WebGL shaders to generate tiles on the fly.

Layer Name

type: string
The unique display name and identifier of the layer. It must be unique and contain no special characters.

URL

type: string
A relative to the mission directoty or absolute file path to a Digital Elevation Map tileset generated by auxillary/1bto4b/rasterstotiles1bto4b.py

Legend

type: string
An absolute or relative file path pointing to a legend.csv that describes the symbology of the layer. Please see the Legend Tool to see how to form a legend.csv.

Initial Visibility

type: bool
Whether the layer is on initially.

Minimum Zoom

type: integer
The lowest (smallest number) zoom level of the tile set.
Note: This field can be automatically populate with “Populate from XML”. “Populate from XML” uses looks for a tilemapresource.xml in the tileset directory specified by the URL field.

Maximum Native Zoom

type: integer
The highest (largest number) zoom level of the tile set.
Note: This field can be automatically populate with “Populate from XML”. “Populate from XML” uses looks for a tilemapresource.xml in the tileset directory specified by the URL field.

Maximum Zoom

type: integer
The highest (largest number) zoom level to see in MMGIS. This value is at least as high as Maximum Native Zoom. This allows zooms level higher than that of the tileset. Instead of rendering new tile image, it scales them in instead.

Bounding Box

type: string optional
A comma separated string defining the tileset’s minimumLonDeg,minimumLatDeg,maximumLonDeg,maximumLatDeg. Setting a bounding box improves performance by limiting requests for tiles to only those that fit the bounds.
Note: This field can be automatically populate with “Populate from XML”. “Populate from XML” uses looks for a tilemapresource.xml in the tileset directory specified by the URL field.

Time Enabled

type: bool
True if the layer is time enabled. URLs that contain {starttime} or {endtime} will be dynamically replaced by their set values when the layer is fetched.

Time Type

type: enum [Global, Individual]
Whether the layer should use global time values or function independently with its own time values.

Time Format

type: string optional
The string format to be used in the URL for {starttime} and {endtime}. Defaults to YYYY-MM-DDTHH:mm:ssZ.

Raw Variables

Data layers need a configured shader raw variable to be effective. Supported shader types are as follows:

  • “colorize”: Allows users to apply and configure dynamic color ramps to the data. Uses the current minimum and maximum viewport data values to adjust color ramps into the most relevant range.
    • units: A string to append to user displayed data values.
    • noDataValues: Values to exclude from minimum and maximum calculations and renderings. Depending on the versions of the custom gdal2tiles, the true data value 0 is represented in the RGBA dem tilesets as 2^31 (2147483648). Ignore 2147483648 as well if you wish to ignore true 0 data values. Max 3 values.
    • sigfigs: How many significant figures to round user displayed values.
    • ramps: An array of arrays of hex color strings. “transparent” is a special keyword for a fully transparent ramp color.
  • “image”: (Default) Simply shows the underlying raw data in an image form. Mainly for testing, it can also be useful for development for internal pass-tile-canvas-instead-of-url layers.

Example:

{
    "shader": {
        "type": "colorize",
        "units": "m",
        "noDataValues": [
            0
        ],
        "sigfigs": 3,
        "ramps": [
            [
                "#FF0000",
                "transparent",
                "#0000FF"
            ]
        ]
    },
    "downloadURL": "(str) url_to_data/data.tif"
}
  • downloadURL: Provides a menu option for users to download the specified source data file for the layer.