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Potato Council Uses the DK-VCL to Develop Interactive Web Mapping Solution

July 08, 2008

By Peter Tickler (ptickler@potato.org.uk)

In April 2008, the Potato Council (www.potato.org.uk - a wholly-owned subsidiary of The Agriculture & Horticulture Development Board) launched an on-line map-based system enabling the growers of England, Scotland and Wales to return details of their potato fields electronically. The intention was that this would gradually replace a paper-based system which currently involves sending out over 5000 maps to nearly 3000 growers.

The system is a web-based system written in Delphi (BDS 2006) using Intraweb and the TatukGIS Developer Kernel Toolkit (VCL edition). It was set up on a Windows 2003 web server, running under IIS. Five different scales of Ordnance Survey maps were utilised.

There are two key elements in any computer system, especially when you have users with a very varied skill-set:

  1. Speed. If it takes more than a couple of seconds to display maps, users are very likely to become disillusioned with the performance of the system. Speed was one reason that we had opted for the DK-VCL, and in practice we were not disappointed.
  2. Simplicity of use Growers only use this system once a year. They would not want to waste a lot of time working out how to use it. It therefore had to be designed to be easy to use. In addition, a help file was provided which they could consult at any time in the process (it opened in a separate window). Navigation was via Zoom in and Zoom out, and via the arrows along each side of the map - these are a standard part of the component. A search button enabled users to find a village by name, or to find a field using its map-reference.

Next to the Zoom-in and Zoom-out radio buttons was an "Add/Edit Plantings" button. When this was turned on, all the user had to do was click on the relevant potato field, and a data entry screen would appear into which the user then enters the hectarage and some other information about each variety in the field.

Behind any easy to use system, there is usually a complex set of code. Using the DK-VCL enabled the programmer to leverage his full set of Delphi skills to ensure the validity of all data entered by the user, and also to trap any irregular user behaviour. Menus and screens were designed to enable users to logon on securely, change password, change the shape and colour of the symbols, and at any stage to review the data entered. A formal process of submitting the completed return was also designed into the system. The scale of the maps displayed at any point was controlled automatically by the Delphi code. Equally a routine was developed which ensured that only the required maps were accessed. These two features, combined with the speed of the DK-VCL components ensured that performance was optimised.

For the 2008 season, just under 200 growers opted to use the system rather than submit paper returns. They were a cross-section of our customers, including some of our smallest and largest potato growing businesses. We hoped that this would result in us being able to manage any problems which might occur. When your customers have a wide range of IT skills, and hardware and software set-ups, it is inevitable that some problems occur. In the event, the problems which did occur were more often than not due to growers losing passwords. The one technical bug which did occur involved a user with a new version of the Safari browser, and that was quickly fixed with the help of TatukGIS's technical support team.

Part of the trialling involved asking users to provide feedback, and this proved to be extremely positive. Ultimately it is the users who tell you if you've developed a good system. "Simple, straightforward, fast, painless. I wish the rest of the season carried on like this!" was one of many encouraging comments. It underlined that Delphi and TatukGIS's Developer Kernel Toolkit make a great combination.

This is the standard map interface that greets the grower. Notice the blue arrows along the edge of the map, the Zoom-in and Zoom-out radio buttons, and the Find Place facility. They offer a simple and easy-to-use navigation system which presupposes no expert knowledge.


This screen enables users to change the colour and type of symbols to meet their personal preferences.


Delphi ensures that a tightly coded data entry screen can be built which prevents invalid data being entered (hopefully!)