Installing GetMapping Aerial Photographs

[Rob_Brookes]

Those of you who have added the GetMapping aerial photos to your version of MRMap will probably know all of this but for those who are contemplating it, hopefully I can make the job slightly more of a background task.

Having now carried out the process several times there are some things to watch out for.

1... Only add the photos for your own region or area. You can add more. You can add as many as you like but the storage requirement on your hard drive becomes silly. There's very nearly half a Terrabyte of photos on the drive I got from Mark Lewis. On top of that the process by which Dave makes MRMap handle large image files without the benefit of an industrial strength compression algorithm is very clever but it does put even more files onto your computer. These are created from the original ones and used during resolution changes, zooming etc. There's nowhere near half a TB of them but they're there non the less.

2... If you happen to have a home network then don't try copying the aerial photos to or from it as it will take hours. It's much the same for the maps as some of you have no doubt discovered. If you're the provider of maps and photos to other members of your team, use a big, external USB-2 drive or DVDs. They're infinately faster.

3... If you have a networked computer running MRMap in your base then ideally don't have the map/image files on a distant drive, it's very slow. This will be a function of your network and not MRMap unless you have a very high speed link. Fit a second hard drive to your computer and put all the maps and aerial photos onto that. This now runs the whole process at optimum speed. 750GB is good.

4... The process by which Dave has MRMap prepare the aerial photos for use requires a lot of background processing time. This can very easily reach 24 hours and during that time the machine needs to be switched on. There are two numbers on the status bar at the bottom of the screen. One is telling you how many maps and aerials the computer has found in your two image folders and the other tells you how many it's processed. When these two numbers are equal then everything is finished and will be running well.

5... Each time you start MRMap it will effectively perform the same routine only now the maps and aerials have already been processed and so the two numbers will quickly assume the same value.
Even whilst processing the image files, MRMap will continue to run relatively normally. Certainly it will receive radio and web position reports and it will track your mobiles. However handling the maps will become very noticably slower until they've all be processed. It's probably best not to try using the aerial photos until they've all been processed. For each 10km x 10km map tile there are 100 1km x 1km aerial photos. These take some loading and manipulating and Dave has achieved a minor miracle in getting the program to use them at all.

6... Dual-core (or more) computers are not strictly necessary but do help and the task of hauling big image files around the screen is easier on a 1.7GHz dual core laptop than it is on a 2.4GHz Pentium 4 desktop. More than 2 cores doesn't appear to make a huge difference but lots of RAM does. You need a minimum of 2GB but that's a generalisation these days anyway. If you run a 64 bit operating system then you will see a big increase in speed from the map handling. MRMap will happily fill up over 1GB of RAM if you have it.

Note : Anyone buying a Windows 7 disk is recommended to use the 64 bit version if you possibly can. It's far and away a better option.

7... When you've finally got all the maps and aerial photos you want to use loaded on to your computer you have to begin the task of processing them. As already said, this really will take about 24 hours and certainly did for the 61GB or so of maps and photos needed for Cumbria. This is obviously best done over night but I'd very strongly suggest that you disconnect your computer from the internet during this time as jolly old Microsoft are just waiting for you to do something like this and have a nice big Windows update waiting for you once you've gone to bed. If your computer decides to shut down and re-boot during this update then MRMap can't finish the image processing at all.

8... Whilst the aerial photos are of value to most teams and certainly work well with their ability to be 50-50 merged with the OS map tiles, you don't have to use aerial photos in the second, 'Aerial', folder. If you have a license to use other OS map tiles at different resolutions then you can use these. Merging them isn't too helpful although MRMap will do it, but switching between different resolutions by selecting 'OS' or 'Photos' can be of benefit. If any team has a licence to use 1:10,000 OS map tiles then these are particularly useful for urban work such as the recent bouts of flooding across the country. It's surprising just how many 'Mountain Rescue' teams are getting to know the streets of their towns and villages these days.

9... The aerial photographs supplied by GetMapping, were in most cases, sent to your MREW regional comms rep and you would get them from this chap or chapesse. If you can't find a source in your own region then contact Mark Lewis. The OS maps were (or should have been!) provided to all affiliated rescue teams in the entire UK but the aerial photos cover a much smaller area at the moment and were not made available to all teams. Again, if you're in any doubt as to how to get hold of these files, contact Mark.

Note : Due to the method of funding the aerial photographs are currently only available in England and Wales.