I read recently that all bar the Sprint maps at JWOC this year used LIDAR surveys as their base maps. I then wondered if anyone has any UK experience of using LIDAR instead of photogrammetry, the Danes clearly having some expertise ...
If so, comments welcome!
LIDAR (Light Detection And Ranging) is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target
LIDAR
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Re: LIDAR
David - there is some interesting stuff here in case you have not seen it -
http://okansas.blogspot.com/
Dave
http://okansas.blogspot.com/
Dave
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DaveK - green
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Re: LIDAR
No experience of using LIDAR data, but available to buy here:
http://www.centremapslive.co.uk/page/height_information
along with cheaper Intermap NEXTMap IFSAR (Interferometric synthetic aperture radar) data (both DEM and DTM datasets). Anyone have experience of using NEXTMap height data for Orienteering maps? On the face of it, it appears to provide sufficient quality at a cheap price.
http://www.centremapslive.co.uk/page/height_information
along with cheaper Intermap NEXTMap IFSAR (Interferometric synthetic aperture radar) data (both DEM and DTM datasets). Anyone have experience of using NEXTMap height data for Orienteering maps? On the face of it, it appears to provide sufficient quality at a cheap price.
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Wayward-O - light green
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Re: LIDAR
Try typing Savernake Forest Lidar into google.
A few years ago, a trial was done to see if Lidar could see through the tree canopy.
They successfully found earthbanks etc. confirming that it is possible.
Perhaps JWOC used this advanced Lidar technique.
A few years ago, a trial was done to see if Lidar could see through the tree canopy.
They successfully found earthbanks etc. confirming that it is possible.
Perhaps JWOC used this advanced Lidar technique.
- martin
- off string
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Re: LIDAR
martin wrote:
Try typing Savernake Forest Lidar into google
I did, and found out that virtually the whole of the Forest of Dean has been covered by LiDAR also. See http://www.gloucestershire.gov.uk/utilities/action/act_download.cfm?mediaid=19092. Must be of interest to NGOC and BOK mappers ...
Big Jon asked
What do these different systems provide in comparison to a good pg plot?
Again, thanks to another post from Wayward-O I found an excellent document which compares all current plotting methods, including photogrammetry and LiDAR, at http://www.centremapslive.co.uk/files/centremapslive_height_data.pdf.
Apart from this, it seems to be increasingly difficult to get pg plots these days, so digital surveying may well be the way forward in the very near future.
Anyone know anything about costs?
- DJM
- diehard
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Re: LIDAR
"Furthermore, photogrammetry often provides more reliable data in areas where LiDAR and IFSAR data are relatively unreliable. Factors such as the coverage of buildings and trees, rapid changes in terrain or steeply sloping terrain, are less likely to result in higher levels of inaccuracies in the data. For instance, photos can clearly define the edges of buildings when the point cloud footprint from LiDAR and IFSAR can not. Conversely, photogrammetry is less reliable in flat and featureless areas."
Excerpt from report - seems to suggest Lidar isn't the be all and end all. What I'd like to know is how does it compare for all info with a pg plot -eg a wooded area pg plot may have variable contour data but will include masses of vegetation details, clearings, changes in height, tree type etc and other data - eg walls, fences, tracks etc. Does Lidar have anything comparable to this or is it just height data?
Excerpt from report - seems to suggest Lidar isn't the be all and end all. What I'd like to know is how does it compare for all info with a pg plot -eg a wooded area pg plot may have variable contour data but will include masses of vegetation details, clearings, changes in height, tree type etc and other data - eg walls, fences, tracks etc. Does Lidar have anything comparable to this or is it just height data?
- Big Jon
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Re: LIDAR
If I'm not mistaken some of this year's WOC maps in Norway were produced using LIDAR base maps.
There's quite a lot of information on its use on the IOF Map Commission web site:
http://lazarus.elte.hu/mc/
If you look under 14th ICOM (International Conference for Orienteering Mapping) there are a number of presentations from various countries.
There's quite a lot of information on its use on the IOF Map Commission web site:
http://lazarus.elte.hu/mc/
If you look under 14th ICOM (International Conference for Orienteering Mapping) there are a number of presentations from various countries.
- redpossum
- yellow
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Re: LIDAR
redpossum said: If I'm not mistaken some of this year's WOC maps in Norway were produced using LIDAR base maps
Yes, according to Havard Tveite (IOF Map Commission Chairman) with regard to WOC 2010 maps:-
Laserscanning data used for contours only
● 1.25 meter contour interval - Terratac
● Contours: extremely accurate - forest or not
● Contours: help identify ditches and cliffs
Which emphasises one big advantage of LiDAR (at least according to my researches today), that it works through forest canopy and results in more accurate contours than does photogrammetry.
- DJM
- diehard
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Re: LIDAR
I think I am right in saying that there may only be one or two people left in the world that produce PG plots these days (Stirling Surveys being one), so there better be a good alternative available soon.
- Paul Frost
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Re: LIDAR
I have used LIDAR data to help me map a couple of small areas for our local events. It is brilliant.
The first area was open sloping ground which was broken up by previous mining activity. There was a tempting collection of depressions, spurs, re-entrants, knolls and low hills, but because no feature differed from the surrounding ground by more than a couple of metres I had immense trouble picking out the mappable features from the indistinct backdrop. I got 1-metre LIDAR data for the area, and it made all the difference. One of the unexpected advantages is that you can view the data in more than one way: contours are the most obvious but there are others. Viewing the data as shaded gradients helped enormously in picking out the features that were distinct and where they ended or started to blur into the background vagueness. With a combination of the shaded gradients, 1-metre contours, and walking the ground, I was able to create a recognisable map of rather difficult ground.
The second area is my current mapping project, a small country park and neighbouring footpaths. The only height information I could find was a single useless 10m contour line. As this ran straight through a high, promint hill, that was no help! Again I got the LIDAR data for the area - and I had my contours. You can plot contours at different intervals, which is really useful for producing accurate form lines. Another benefit is that with 1 or 2-metre intervals, small features or changes in the ground that are worth investigating become immediately visible.
Buildings can be seen, as ghostly blocks of non-data, but are not a distorting influence. The main drawback is getting the data out for use in OCAD. I use the trial version of Global Mapper to produce the contour and gradient images, but the trial version does not allow exporting images, so I have to use screenshots or screen grabbing software. Not ideal, but it does the job. Unless I or my club are willing to spend getting on for £300, the trial version it will be! The only other, minor drawback is that it is a little fiddly to get the images located exactly in the right place as a background in OCAD. However, as the data comes with OS co-ordinates, and I use OS 1:10000 for base maps, it can be done!
As you might guess, I'm a fan of using LIDAr data, when the circumstances warrant it.
The first area was open sloping ground which was broken up by previous mining activity. There was a tempting collection of depressions, spurs, re-entrants, knolls and low hills, but because no feature differed from the surrounding ground by more than a couple of metres I had immense trouble picking out the mappable features from the indistinct backdrop. I got 1-metre LIDAR data for the area, and it made all the difference. One of the unexpected advantages is that you can view the data in more than one way: contours are the most obvious but there are others. Viewing the data as shaded gradients helped enormously in picking out the features that were distinct and where they ended or started to blur into the background vagueness. With a combination of the shaded gradients, 1-metre contours, and walking the ground, I was able to create a recognisable map of rather difficult ground.
The second area is my current mapping project, a small country park and neighbouring footpaths. The only height information I could find was a single useless 10m contour line. As this ran straight through a high, promint hill, that was no help! Again I got the LIDAR data for the area - and I had my contours. You can plot contours at different intervals, which is really useful for producing accurate form lines. Another benefit is that with 1 or 2-metre intervals, small features or changes in the ground that are worth investigating become immediately visible.
Buildings can be seen, as ghostly blocks of non-data, but are not a distorting influence. The main drawback is getting the data out for use in OCAD. I use the trial version of Global Mapper to produce the contour and gradient images, but the trial version does not allow exporting images, so I have to use screenshots or screen grabbing software. Not ideal, but it does the job. Unless I or my club are willing to spend getting on for £300, the trial version it will be! The only other, minor drawback is that it is a little fiddly to get the images located exactly in the right place as a background in OCAD. However, as the data comes with OS co-ordinates, and I use OS 1:10000 for base maps, it can be done!
As you might guess, I'm a fan of using LIDAr data, when the circumstances warrant it.
- dustytoo
- white
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Re: LIDAR
I got my data from Geostore (http://www.geostore.com). I like the fact that it has an instant pricing facility. Basically, select Buy Now, use the tools on the right to select an area of interest, which gives an aerial photo. Use the tools to then identify an Order Area. Below the aerial photo, select the Height Information Products. Select the type of data you require, then select the tick box to the right of the Not Priced label for the preferred product - the price for the area you have identified is given.
Note, the availability of the various kinds of height data will vary depending on the area - for example LIDAR 1-metre data is mostly available for urban areas, I believe.
Pricing seems to be based on the resolution of the data and the size of area. To give some idea, an area the equivalent of a 1km square on the OS 1:10000 is about £75.00 (ex VAT) for LIDAR 1-metre data (I have used this) . The equivalent area for Digital Terrain Data 5-metre would cost about £10.00. From what I have seen elsewhere recently, DTD data is fine for contours, and pretty accurate interpolations for smaller contour intervals are possible.
Another nice feature of the Geostore site is that when you select your preferred type of data, the aerial image changes to give an image of the terrain, and this can be quite instructive.
I am by no means an expert in this stuff, but i've found it useful, so if you want any more detailed info, PM me.
Note, the availability of the various kinds of height data will vary depending on the area - for example LIDAR 1-metre data is mostly available for urban areas, I believe.
Pricing seems to be based on the resolution of the data and the size of area. To give some idea, an area the equivalent of a 1km square on the OS 1:10000 is about £75.00 (ex VAT) for LIDAR 1-metre data (I have used this) . The equivalent area for Digital Terrain Data 5-metre would cost about £10.00. From what I have seen elsewhere recently, DTD data is fine for contours, and pretty accurate interpolations for smaller contour intervals are possible.
Another nice feature of the Geostore site is that when you select your preferred type of data, the aerial image changes to give an image of the terrain, and this can be quite instructive.
I am by no means an expert in this stuff, but i've found it useful, so if you want any more detailed info, PM me.
- dustytoo
- white
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Re: LIDAR
GeoStore doesn't seem to list anything in Scotland, so I guess there must be another supplier?
- Paul Frost
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