Lidar used to be exotic and expensive, but no longer! Cutting edge, archaeological  aerial survey techniques are now free for us to use.

Here is an example

Smallshaw_ditches_crop
Smallshaw, note the three ditches of the prehistoric enclosure and the image “shows” the ground  under the tree cover!

Here is a standard aerial view.

hill-fort_inv

Lidar image bank

Get your Lidar images here

Example
The link example directs to OS grid reference SD 81, which covers most of west Rochdale.

The Ordnance Survey National Grid Reference System

See more about the OS grid reference system  here.

Selecting an OS grid square

Select a grid reference by entering the OS grid or move the map with your mouse or by touch.

SD81selected

Example
Enter SD81 to select the grid that covers west Rochdale.

Download and process your Lidar images

  1. Select the grid you are interested in (SD81 in our example).
  2. Create a directory on your pc, or other device for the group on files you download, example SD81
  3. Select a group of files to download  from the bottom of the display
    (the different file types and what they mean are explained here)
  4. Select DSM (in this example) at 1m resolution for SD81.
    SD81_DSM_at_1m
  5. The files are a zip archive of 180.3MB!
  6. Select the green download icon to download the zip archive.
    click2download.jpg
  7. Download the zip files to your directory (SD81 for example)
  8. Unzip the files with a compatible program (I used the free Pea zip, there are many others)
  9. You directory, with the unzipped files should look like these names, they are ASC file format.ascfiles
  10. These ASC files have to be converted into images you can view, use a GIS system if you have access to one (lucky you!), if not…go to step 11.
  11. To decode ASC files without a GIS system download the Relief Visualization Toolbox (RVT) for your operating system (currently supports Windows and Linux 64 ) from the Research Centre of the Slovenian Academy of Sciences and Arts.
  12. Download the RVT (for example rvt_1.1_win64 for Windows 7) and then unzip the files to a directory.
  13. Install the software, you should then see this
    IDL
  14. Select click to continue and then you will see
    reiefvistoolbox
  15. Select addfiles.jpg add the ASC files in your directory (SD81 in our example).
  16. Your directory should look like this:
    SD81DSM1ASCfiles
  17. Load all the files and use the default settings for now and then select “Start”.
  18. This will take time depending on the speed of your computer.
  19. When the process is complete your directory should now have graphic files (TIFF format) created alongside the .ASC files.
  20. View these files with any program that can read and display the TIFF images, I used a free program called IrfanView.
  21. Here is a selection from one of the images, know what is in the centre? send me a message if you do please! -:) it’s old and it is north of Bury!
    mystery feature

Want to install your own GIS system?

LandSerf is a free GIS system which runs on any platform that supports the Java Runtime Environment (Windows, MacOSX, Unix, Linux etc.)

Too much work?

Try this site, just zoom in to explore your region (some areas do not have Lidar coverage). Note you do not have the choice of surface or terrain Lidar images.

Thanks to…

Special thanks to Marcus Jecock of Historic England for telling me about the Lidar source files and the software to decode the ASC files.

The software to decode the Lidar source files is from Slovenia’s Institute of Anthropological and Spatial Studies and is funded by the EU, see more details here.

James Moran-Zietek for telling me about LandSerf.

Under construction…

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s