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The .asc LiDAR files provided by the environment agency have height values provided to a precision of the level used to measure atoms. How to quickly lose a few of the pointless digits on the end to get from attometers to centimetres?

There must be a simple solution but I can't see it.

I have tried raster calculator but the results of the calculation below are still in attometers.


marked as duplicate by Andre Silva, whyzar, LaughU, KHibma, csk Nov 2 '18 at 20:40

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  • 1
    Can you post view example lines of your lidar data. Normally you can use python or perl to parse x, y and z of each line, scale the z value and write x, y z back to an other file. – huckfinn Feb 29 '16 at 11:19
  • Please formulate questions and answers in a more precise way. The link you send contains several archives. If you choose the archive LIDAR-DTM-2m.zip, you will find 100 .asc files inside. If you select the first one tl7000_DTM_2m.asc you can find out with gdalinfo that it is a ArcInfo ASCII Grid files with 1 mm vertical resolution: gdalinfo tl7000_DTM_2m.asc Driver: AAIGrid/Arc/Info ASCII Grid Files: tl7000_DTM_2m.asc Size is 500, 500 Coordinate System is `' Origin = (570000.000000000000000,201000.000000000000000) Pixel Size = (2.000000000000000,-2.000000000000000) Corner Coordinates: Up – huckfinn Feb 29 '16 at 12:21
  • Usually I think there is no meaningful storage or processing cost to these extra digits in the end, they are simply using the maximum storable range for the field data type. In this case I would guess it is some sort of long int 4 byte type. Obviously it would be strange to report these levels of precision but it usually does no harm to store them. Am I wrong? – Alexander Feb 29 '16 at 15:07
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    The question is quite precise. Reduce the precision of .asc files in qgis. I can get the results via .xyz and some other software but I want to reduce the precision in Qgis. I could write a very long detailed explanation of the issue and the data but the question is still pretty simple. – Sethinacan Feb 29 '16 at 15:46