Zmapping - FAQs

1.	What are your models used for?

2.	Do you sell software or data?
3.	How do I go about getting a quote or ordering a model from you?
4.	What technology do you use to make the models?

5.	Which co-ordinate system are the models based on?

6.	How accurate are your models?

7.	Do your models follow landscape and terrain?

8.	What do your 3D models include, and what do they not include?
9.	Is there a limit to the area you can produce?

10.	Can you produce your models at varying levels of detail?

11.	Do you sell aerial photographs?
12.	Your models are interactive. What does this mean?

13.	Can I release a model over the Internet?

14.	What software will I need to use your models?

15.	Do I need special hardware to use your models?

16.	How can I use your models for 3D GIS?

17.	The GIS software I use can create 3D models. How are they different from yours?

18.	I need a physical model of a block of buildings. What can you do for me?

1. What are your models used for?
In the construction industry, our 3D models are regularly used for visualising new developments in existing surroundings. The integration between the old and the new means that a range of technical assessments can be carried out with ease and great accuracy. Digital 3D models are particularly useful tools during the planning application process.

For the emergency services, our models are particularly useful for security planning and crime scene investigation. In the telecommunications sector, 3D models are used for mast installations. Other users include large property owners, real estate agencies and insurance companies. Our models are also used by scientists carrying out various environmental tests.

2. Do you sell software or data?
We sell data. Our models are digital files that an be used for a multitude of purposes. In order to run them you need use them with the appropriate software; we do not provide any software in which to run them.

Also see What software will I need to use your models? and Do I need special hardware to use your models?

3. How do I go about getting a quote or ordering a model from you?
For a quote, please send us a map with the area you are interested in clearly outlined, together with the post code of a central area, if available. Indicate a deadline by which you will need to receive the complete model. We will then get back to you with a quote within three working days. Our price is relative to the amount of area to be covered.

4. What technology do you use to make the models?
Our 3D models are produced using the technology of photogrammetry – the method of deriving vertical and horizontal co-ordinates from stereo aerial photographs. Photogrammetry is superior to other technologies in producing accurate, detailed, models, which again enable the creation of photorealistic interfaces for the public.

5. Which co-ordinate system are the models based on?
The model sits on the exact geographic co-ordinates represented by the Ordnance Survey (OS). This means that in the UK, the origin (0,0,0) of the model is near Cornwall and the X-Y co-ordinates will be the same as OS landline maps.

6. How accurate are your models?
For projects requiring the highest accuracy, the variation of measurement achieved from a ground survey of any point compared with the same point measured off from our model can be as small as 5 centimetres.

For the average model, however, we will only claim an accuracy of around 50cms. This is because the accuracy of any model depends on the data supplied. This will come in the form of stereo aerial photographs taken at a particular resolution. The higher the resolution, the better the accuracy. In addition, GPS ground control points can be taken, which will also boost accuracy.

It is worth noting that geographic co-ordinates can be read off our models. For example, an air vent measuring 1.9 x 1.75 metres on the roof of London’s National Gallery, at 529905.95 easting and 180557.95 northing, is visible on Zmapping’s 3D model with exactly the same dimensional and positional information.

Zmapping models and OS landline maps match without any noticeable differences.

7. Do your models follow landscape and terrain?
Yes. Our models are created to true terrain levels and landscape. There are no 'steps' or 'blocks'. A Zmapping model is intended as a digital replica of your surroundings.

8. What do your 3D models include, and what do they not include?
Our models include buildings, roads, bridges, land (including pavements), trees (where practicable) and water features, all provided in separate layers. The models are not textured or rendered, the idea being that the layered objects allow the user to have full control over the model and render it whichever way is desired.

See also Do your models follow landscape and terrain?

9. Is there a limit to the area you can produce?
No. We can do a few buildings or an entire country. In essence, we can do any area of any size, anywhere in the world, provided data and resources are available.

A very large model we will splice into sensible portions, for instance by post codes, which can then be loaded according to the areas you need.

10. Can you produce your models at varying levels of detail?
Yes, we can. As well as high resolution models, we can produce wire frame models together with even simpler height models.

A wire frame model can be detailed enough to capture objects as small as a 20x20cm roof light. A simple height model will have the level at ground, level of the highest point of the building, height of the building and also classify the roof as flat, pitched, mixed, varying height and so on as per your requirement. This is our most basic product.

11. Do you sell aerial photographs?
No, we don't, even though we use photography in the production of our 3D models and we do pass the cost for this on to the client. In the event that you procure a model from us, you can obtain your own copy of the photographs from our suppliers, should you wish. We will provide you with a reference number for you to quote upon contacting them.

12. Your models are interactive. What does this mean?
It means that you, as the user, have full control over how you display and move about in your digital 3D environment. You can zoom in and out, orbit and view parts from any direction and display and manipulate the model as you wish. You can ‘take a walk through town’ by going down to street level and turning corners, or make a route and ‘fly’ through it for added impact.

13. Can I release a model over the Internet?
Yes. VRML files can be generated and released to the public over the internet, for people to view in free and easily downloadable viewers on their own computers. The user can ‘walk’ and ‘fly’ round the various parts of the model, as you would in the original model.

14. What software will I need to use your models?
We produce our models such that they can be used in most popular CAD packages, such as AutoCAD, AutoCAD Map, Microstation, Rhinoceros and 3D Studio. We can supply the models in most popular formats like DWG, DXF, DGN and 3DS. One of the most economic pieces of software is Rhinoceros which is available for about £400. Inexpensive, or even free, viewers are also available for those who merely wish to roam around the model.

15. Do I need special hardware to use your models?
The majority of today’s computers can handle the load very well. For instance, a Pentium 1 GHz with 128MB RAM will allow you to work on 1 km^² of buildings and roads at any time. A Pentium 2.5 GHz with 512 MB RAM can easily load more than 3 km², as well as display the model in colour shaded mode and perform fly-throughs in real time. A single CD will hold an area of 50 km² – in other words a whole town.

16. How can I use your models for 3D GIS?
Our models can be directly opened in AutoCAD Map, shaded, rendered and data can be added. Other popular GIS packages that support 3D will also import DXF directly or by means of simple conversion. For example, our model can be converted to an ESRI shape file (SHP) for use with ArcView. 3D GIS being a new major step, most new packages will support new features specifically for 3D use.

17. The GIS software I use can create 3D models. How are they different from yours?
Many GIS applications these days can create very basic 3D models. Mostly, this is a simple operation of feeding in a height to the existing 2D building footprints. The resulting buildings all have a flat roof. Thus they may be usable to a certain extent for some specific uses such as building height restrictions in airport zones. But they will be unusable for most other presentation or analytical purposes discussed on this web site.

18. I need a physical model of a block of buildings. What can you do for me?
Our models can be optimised for export to a rapid prototyping machine. This way, physical models can be derived from our digital models.

Derived from photogrammetry, the dimensions of the physical model will be geographically accurate, though scaled down.

Read more under Derived Physical Models.