Woodward I.T. NRC GIS Internet ActiveX

Woodward IT is a partner of:

The Northern Rivers Councils is a group of 5 Councils on the northern border of NSW. Together they were looking to fund an internet project whereby customers could look up a property or request a report online rather than coming to the counter.

One of their first steps was to build an interactive GIS tool that could be used by their customers online. The problem they had was that different GIS packages were used at each council. In order to make each Council's site have the same appearance, they decided to develop their own GIS web deployment facility. Therefore, the Councils of NRC would not have to pay 5 lots of support for a commercial GIS product.

The premise was to use Microsoft products such as IIS and SQLServer on an NT machine. This requirement could be met by every Council. On top of which Woodward IT was contracted to build a prototype internet tool to create images from coordinates stored in SQLServer.

Upon studying possible scenarios, the end result was to develop an ActiveX DLL that could be instantiated from ASP pages. The end product had to be able to support any browser, so the full prototype (including web pages) used a combination of ActiveX, ADO, JavaScript (client side), vbScript (server side), ASP and a whole stack of SQL. The ActiveX control is responsible for viewport mapping, memory bitmapping, Windows GDI calls and JPEG generation. The result was an extremely quick product capable of returning excellent results.

ASP Make Up

Because the ActiveX control sits on your web server, the content or feel of your web page can be totally controlled by your web developers. The ActiveX control has a variety of methods including a start window method, which will draw a starting reference window.

The web developer simply sets a height and width of the image required and the ActiveX control returns a handle to the JPEG image it creates.

Cadastre

The ActiveX control is passed the MBR required to redraw in and then displays the layers passed to it. By default, you cadastre is one of the primary layers you will want to display.

When you extract your GIS data, you can also specify the look of each layer. For the cadastre you can specify whether to plot a border for each property and also whether you want to shade each property and its colour.

Point, Line and Area Features Supported.

The ActiveX control supports the display of layers containing points, lines or areas or a combination of each. As well as this, rotated text is also supported.

There is a set of different symbologies that you can apply to your lines and points, which can be defined when your GIS data is extracted.

Layer Management

Part of the ActiveX control is layer management. Originally you define the order of layers and the scale thresholds at which they can be displayed. You can also define whether these layers can be turned on or off by the user. For instance, you will always want your cadastre layer on, so set it up so it does not appear in the Layer Manager.

Once again, the actual layer control is handled by an ASP page of your design, which then sends to the ActiveX control, the layers to be displayed.

Continue to GIS Internet ActiveX Page 2 ->