TMS Task
A TMS task converts georeferenced raster data into a tiled raster dataset based on the Tile Map Service specification. Further information can be found here.
Zoom Levels and resolution
The following table shows which zoom level corresponds to which resolution:
| Resolution | Maximum Level |
|---|---|
< 0.0375 m |
23 |
< 0.075 m |
22 |
< 0.15 m |
21 |
< 0.3 m |
20 |
< 0.6 m |
19 |
< 1.2 m |
18 |
< 2.4 m |
17 |
< 4.8 m |
16 |
< 9.6 m |
15 |
< 19.2 m |
14 |
< 38.4 m |
13 |
Step 1
| Option | Description |
|---|---|
Task Name |
Name of the task. |
Create or overwrite Datasource |
Select whether to create a new datasource or overwrite an existing one |
Datasource Name |
If an existing data source is to be overwritten, select the source here. |
Step 2
In this step, you specify the information needed to convert georeferenced images. The mandatory parameters are displayed prominently in the settings panel. Additional optional parameters are available under Advanced Settings.
Below, you will find a description of the minimum required parameters.
| Setting | Description |
|---|---|
Path to input data |
The conversion process requires the path to the directory, including the file extension, if multiple files should be considered (path*.tif/jpg). Alternatively, the path to the directory with the exact file name and extension can be specified (path\file.tif/jpg). |
EPSG Code |
Specifies the coordinate reference system of the imagery datasets as an EPSG code. |
Format |
Determines the format into which the images will be converted. The options are JPEG or PNG. For JPEG, the JPEG quality can be adjusted. The PNG format allows specifying a NodataValue, which is used to classify pixels—usually at the edge of an image—as transparent, so that they appear transparent in the viewer. |
Nodata Value |
Enter the value of the pixels that should be transparent. For example, enter “255” if black pixels should be classified as transparent and each of their RGB channels has the value “255”. |
Resampling Method |
Several methods are available. “average” is considered the most balanced option in terms of compression capability and image quality for resampling. |
Next are the advanced settings. These settings are optional. If no values are entered, default parameters will be used:
| Setting | Description |
|---|---|
Number of Threads |
Number of allowed simultaneous operations. More threads allow the converter to use more of the computer’s resources for the tiling process. By default, four threads are allowed simultaneously. |
Additional optional parameters GDALBuildVRT |
Optional parameters can be specified to adjust the GDALBuildVRT process. Relevant parameters can be found here: https://gdal.org/en/stable/programs/gdalbuildvrt.html |
Additional optional parameters GDAL2Tiles |
Optional parameters can be specified to adjust the GDAL2Tiles process. A common example is the “-z” parameter, which allows manual definition of which levels should be generated. By default, the process inspects pixel resolution and creates the appropriate level structure automatically. A reference for which resolution corresponds to which level can be found above. This can be adjusted if needed, for example by specifying “-z 16-21”. Additional parameters can be found here: https://gdal.org/en/stable/programs/gdal2tiles.html |