# Cadcorp SIS
The Cadcorp Spatial Information System (Cadcorp SIS) is an integrated family of geospatial products comprising desktop, web, and developer applications.
Cadcorp SIS Desktop and Cadcorp SIS Desktop Express (free) connects directly to the Ordnance Survey Data Hub through dedicated wizards.
These instructions demonstrate how to integrate and apply the OS Features API into Cadcorp SIS in order to produce a series of topography layers based on our latest OS MasterMap Topography layer data.
## What you need?
* Cadcorp SIS Desktop or Cadcorp SIS Desktop Express (free) version 9 or later
* A preloaded base map, for example, [os-maps-api](https://docs.os.uk/os-apis/accessing-os-apis/os-maps-api "mention") or [os-vector-tile-api](https://docs.os.uk/os-apis/accessing-os-apis/os-vector-tile-api "mention")
* OS Features API URL and key; see [getting-started-with-an-api-project](https://docs.os.uk/os-apis/core-concepts/getting-started-with-an-api-project "mention") for more information
## Instructions
{% hint style="info" %}
We used Cadcorp SIS Desktop Express version 9.0.2275 to create these instructions
{% endhint %}
1. Start Cadcorp SIS Desktop. In the opening window, select *Blank Map* or a map template with pre-defined base mapping in the Map Templates area.
2. Navigate to *Home > Add Overlay* to launch the Add Overlay wizard.
3. In the Overlay Types dialog, navigate to *Ordnance Survey (GB) > OS (GB) Data Hub* and then click *Next*.
4. In the OS (GB) Data Hub dialog:
* If you do NOT have an API key, select the OS Features API, click *Next* and then select *Yes* in the confirmatory dialog that opens. This will use the standard Cadcorp API Key. Note this key restricts your access to free open data and you will not be able to access Premium features.
* If you have an API key, select the *OS Features API,* enter your key in the API Key field, check the *Premium Plan* option and then click *Next*.
5. In the OS Data Hub Features API Products and Feature Types dialog:
* **Left** box: Select the OS Features API product you want to add to the map. When you do this a list of available feature types for the selected layer display in the Feature Types box (right box).
* **Right** box: Select the feature types you want to add in the right box by deselecting the feature types you do not require.. All features are selected by default.
* **Theme**: Select the style for the map in the dropdown. This option is only applicable to some\_ OS Features API layers\_.
* **Local cache/One-off import**: Select an option to either store locally or download as one-off import.
* **Filtering**: You can also optionally load features within a specific area of interest (as opposed to the extent of the current map window). See [Defining your area of interest using a polygon](#defining-your-area-of-interest-using-a-polygon) below for instructions.
6. Click *Finish* to add the layer to the map.
7. The selected features will load within the current map extent. As a best practice, we recommend that you keep the number of features to a minimum.
### Defining your area of interest using a polygon
As an alternative to loading feature to the extent of the current map window, you can use the filtering options available in the OS Data Hub Features API Products and Feature Types dialog (step 5 above).
To do this follow all steps in the instructions above, with the following exceptions:
* Before launching the Add Overlay wizard (step 2 above), select the polygon feature on the map for your area of interest.
* In the OS Data Hub Features API Products and Feature Types dialog (step 5 above), additionally set filtering options in the Filtering area:
* **Spatial**: Select *Spatial test with current item extent*. If you prefer a different spatial test , select ‘Spatial test with current item’, and this will activate the Spatial test dropdown menu where you can select your spatial test of choice.
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