Overview

If you have a PSMA licence then you have access to the nationwide WMS of the latest Aerial Photography from APGB. This can be loaded into iShare and used as a source for a BaseMap. The following tutorial describes how to create such a BaseMap. 

Create a BaseMaps Map Source

The best way to create a new Map Source for your Aerial Photography BaseMap is to copy an existing Map Source.

• Open Studio
• Right click on the BaseMaps node and select Create MapSource.
• Select an existing Map Source to copy and click OK.
• Give it a new name e.g. base_Aerial_APGB and click Save.
• Now you need to change the Display Name in the Explorer e.g. Aerial APGB.
• Click on the Details node in the Explorer under your new Aerial APGB BaseMap and enter the following:
  • Name: this is going to be the layer name you want to make use of from the APGB WMS e.g. AP-12CM5-UK-WMS
  • URI: this is going to be the APGB WMS URL. 
  • The .map file is not used.

• Save your changes.
• You may have to reduce the scale range to a maximum scale of 22677.1776. In our tests the 12.5cm WMS from APGB would return correct images for this scale and below.

Add the Aerial Photography BaseMap to My Maps

Now that you have created your new Aerial Photography BaseMap you need to make this available in your My Maps Map Source(s).

• Expand the MyMaps node in Studio and select the Map Source entry (Profile) where you wish to make this BaseMap available.
• With the MapSource tab selected. select your new BaseMap from the list of Available entries and use the arrows provided to add it to the list of Selected entries.
• Save your changes.

Enable Ciphers

The server must support a certain type of cipher. Download and run IIS Crypto from Nartac and go to the Cipher Suite section. Enable either TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 or TLS_DHE_RSA_WITH_AES_128_GCM_SHA384. A reboot will be required.

Using APGB Historic Imagery

As well as providing a WMS hosting the most recent captured imagery APGB also makes available Historic Aerial RGB and Infra-red Imagery and Terrain models. To make use of the Historic or Infra-red imagery in iShare Maps or iShare GIS a PSMA member will need to first download the data and then create a BaseMap. The BaseMap will be a WMS BaseMap but this may sit behind either a Dynamic Tilecache or a full pre-seeded Tilecache. 

Tilecaches increase performance by removing real time rendering. Before we consider Tilecaches it is advisable to first process the imagery so that the files can be displayed quickly. We want to avoid compressed file formats and unnecessary bloat to files. Read Convert Rasters for Map Serving on how best to convert the files.

Next read Configuring Raster Layers on how to create a tileindex for a set of raster files and create a layer definition in a .map file.

Read Configure MapServer to be a WMS or WFS Server to make sure the .map file is WMS enabled.

The .map file can now be used as the basis for a BaseMap identical to the instructions above. Use your MapServer public URL and call upon the correct Group or Layer name.

This will create a WMS BaseMap using the source data. As there is no application-level caching it is advisable to check the performance is adequate. Historic Imagery is called upon far less than recent Aerial Photography so most people would set up a cache of their latest aerial imagery but not for their historic imagery.

If performance needs to be improved the next step would be to introduce either a pre-seeded Tilecache or a Dynamic Tilecache. Read Create a Dynamic Tilecache for advice on how to set up a Dynamic Tilecache and The Tilecache for pre-seeded Tilecaches or speak to your Astun Consultant for assistance.