Frequently Asked Questions
What does orthorectified mean?
In layman's terms, orthorectified means that the photographic images have been draped over a 3D model of the earth to remove any distortions caused by the shape of the earth and tied to a ground coordinate system. As a result, the images become TRUE TO SCALE and DISTORTION FREE. Further, because the images are tied to surveyed ground coordinates all data is in the true position - allowing ACCURATE measurement of any detail on the image.
What scale are the images?
Because the images are digital, they are effectively SCALE-LESS, on a computer you can zoom in or out to any scale you want. As a guide, most photography held by Plateau Images has been flown at 1:25,000 scale - this gives a good quality image over very large areas at an economical price. This film based photography is scanned at very high resolution to create a digital image which is quite clear at scales down to 1:2,000. If you go to a larger scale (say 1:1,000) the images will become blurry or pixellated.
Is it as good as satellite imagery?
It's BETTER! The clarity of an image is called pixel resolution - the smaller the pixel size, the more crisp the image looks. The best pixel resolution commercially available from satellites in colour images is about 0.6m - and this is after resampling an original 2.4m colour pixel against a black and white image of the same area to create a sharper look for the colour image. The majority of Plateau Images data is 0.5m pixel resolution - TRUE capture. Some data is 0.2m resolution. Beware of cheap satellite images - they won't be as good an image quality and they are probably not orthorectified. Also ask what date the images were captured before buying anything as you may be getting a poorer quality image which is many years out of date.
How long will it take to get the data once I order it?
All data on our indexes currently exists ON THE SHELF (except where shown). Therefore, once you order it - it generally takes only one or two days to be in your hands. No waiting for clear weather or aircraft availability - or waiting a month for satellite data from the US.
I have a large property - how many images will it be on?
ONE!! - since the data is digital, there is almost no restriction. The data is a seamless data set and any area can be cropped out to suit your needs.
My area isn't on the indexes, what do I do?
Contact Plateau Images to see what areas we are producing in the near future.
What Scale is the Source Photography?
1:25,000
What Format do you use?
24 bit images in Geotiff, ECW (compression ratio 10) or JPG format, with Mapinfo .TAB file available if required.
What media are the tiles supplied on?
CD or DVD as required.
What are the tile's file size?
Geotiff files around 80 Mb - JPG and ECW under 10 Mb each tile.
Do the tiles contain void space?
No tiles contain void spaces.
Please contact us if you have any further questions.