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LIDAR availability?

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  • 08-01-2015 10:14pm
    #1
    baaba maal
    Registered Users Posts: 772 ✭✭✭


    My understanding is that the OSI have large swathes of the country already LIDARed. Although it isn't advertised on their website, I am led to believe that they will sell access to it to institutions etc. for research purposes.

    So why isn't it available more readily to amateurs with an interest in the area (such as myself)? I imagine a lot of unknown sites will become apparent but is access restricted to prevent discovery (leading to damage and theft) or am I missing something?

    I have seen one or areas I am familiar with through LIDAR and it is simply stunning in terms of the palimpsest revealed, so as a resource it has amazing potential (although the threat to sites must also be factored in).

    Opinion, fact and speculation welcomed......


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    #2
    Meathlass
    Registered Users Posts: 3,023 ✭✭✭Meathlass


    Our local group bought the maps covering our area. I don't think it's restricted to research institutions.


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    #3
    RDM_83 again
    Closed Accounts Posts: 4,116 ✭✭✭RDM_83 again


    I think all of county Dublin has a LIDAR survey with a 0.5 meter resolutions anyway, the Boyne area as well has had a high resolution LiDAR carried out on it AFAIK.

    You can certainly buy the LiDAR data from the OSI as a private company, I'm not sure if it will eventually free to obtain.
    Be warned though it doesn't come in the easiest format to work with initially.

    Personally I've been a bit disappointed with the LiDAR I've worked with, it looks very nice but I think heavy agricultural activity removed any traces of sub surface archaeology


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    #4
    baaba maal
    Registered Users Posts: 772 ✭✭✭baaba maal


    The bit I have seen is actually southwest Dublin/Kildare border and it is (to my mind) stunning in the detail that is otherwise not apparent. Everything from simple tracks (I think they might be called drovers ways?) to, enclosures and completely unknown barrows. It is heavily worked tillage and pasture, but it is hilly and that probably saves a lot of features.

    I presume you mean that "you can buy it from the OSI as private company" would include regular individuals? I must actually see the software requirements- I would think it would be fascinating to be able to compare LiDAR with the corresponding bing map of an area. Probably out of my price point and technical ability but ya gotta have a dream.

    Still think it odd that the OSI went to the expense of mapping areas in LiDAR and then didn't try to turn it into an actual product, considering they are in the business of selling maps!


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    #5
    slowburner
    Moderators, Science, Health & Environment Moderators Posts: 5,218 Mod ✭✭✭✭slowburner


    I have to confess that much of the technology surrounding LiDar is way out of my understanding. That said, I have seen some stunning revelations, features that would never be seen with existing imagery or even on the ground.
    I have also seen some very mediocre results - possibly inferior to the battery of image sources freely available online.
    As far as I understand it, some topographies are difficult for LiDar. These include bogs or wetlands and typical upland vegetation patterns characterised by low, dense scrub such as heathers and upland furze.
    Dr. Steve Davis of UCD has made some stunning discoveries nationwide through LiDar. I was lucky to be involved in surface verification for one of them and can guarantee that that important monument would never have been found any other way.
    By the way, a valued contributor here - Simon Dowling - is at the forefront of developments in manipulating aerial photo data to a level equal to or even surpassing LiDar.


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    #6
    RDM_83 again
    Closed Accounts Posts: 4,116 ✭✭✭RDM_83 again


    baaba maal wrote: »
    The bit I have seen is actually southwest Dublin/Kildare border and it is (to my mind) stunning in the detail that is otherwise not apparent. Everything from simple tracks (I think they might be called drovers ways?) to, enclosures and completely unknown barrows. It is heavily worked tillage and pasture, but it is hilly and that probably saves a lot of features.

    I presume you mean that "you can buy it from the OSI as private company" would include regular individuals? I must actually see the software requirements- I would think it would be fascinating to be able to compare LiDAR with the corresponding bing map of an area. Probably out of my price point and technical ability but ya gotta have a dream.

    Still think it odd that the OSI went to the expense of mapping areas in LiDAR and then didn't try to turn it into an actual product, considering they are in the business of selling maps!

    I was only looking at a fairly small area so while it looks lovely I'm not sure it revealed anything significant.

    They do sell it as a product as far as I know, its just you have to email them and tell them what area you want to look at.
    Its a relatively processor heavy work but if your looking at smaller areas or you set it up to be tiled it can be done on a reasonably decent laptop.
    This link here should do the job.
    http://www.osi.ie/Products/Professional-Mapping/Height-Data.aspx

    They will then send you a file containing the X,Y,Z data in a massive text file. I found this stage a bit fiddly as its too large for programs like excel to handle but you can use alternatives.
    Then you can download the freeware QGIS and create a raster from the data within that file, then apply a hillshade and you should have something nice to work with.
    Personally I use ArcGIS so I'm not able to advise in the detail of how to manipulate the data using QGIS.
    I'm not sure how much free LIDAR data you can get for Ireland but take a browse of this site,
    http://www.opentopography.org/index.php
    If your just wanting to work to familiarize yourself with the process I think Finland has a lot of free data available.

    Edit: Oh and its very useful to know what the acronyms refer to!


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    #7
    baaba maal
    Registered Users Posts: 772 ✭✭✭baaba maal


    Thanks RDM- you've actually explained in simple terms something I thought I wouldn't be able to understand! I have some relatively techie friends so we should be able to work through it. They probably charge by the 100 metres (or less!) so I'll have to pick likely areas!!

    And thanks Slowburner- I was fortunate enough to spend an hour with Steve going through a couple of areas I was familiar with, just brilliant.
    Yes, LiDAR certainly has limits. Although I think they can manipulate the data from wooded areas better than previously, it is still a serious impediment ( the Moate of Ardschull is one site I would love to see with the trees<digitally> removed- we wouldn't learn anything from this, I would just love to be able to see it without the distraction of the trees!).


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    #8
    RDM_83 again
    Closed Accounts Posts: 4,116 ✭✭✭RDM_83 again


    baaba maal wrote: »
    Yes, LiDAR certainly has limits. Although I think they can manipulate the data from wooded areas better than previously, it is still a serious impediment ( the Moate of Ardschull is one site I would love to see with the trees<digitally> removed- we wouldn't learn anything from this, I would just love to be able to see it without the distraction of the trees!).

    There is plenty of good tutorials online but you are likely to encounter a simple but frustrating problem that you can spend hours trying to fix it (in my experience anyway).

    The issue you are talking about there is why I think it is very useful to know the acronyms

    300px-DTM_DSM.png

    This thread here has more detail about the correct terminology

    http://gis.stackexchange.com/questions/5701/what-is-the-difference-between-dem-dsm-and-dtm


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    #9
    baaba maal
    Registered Users Posts: 772 ✭✭✭baaba maal


    Wow- much to process! Many thanks.


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