Thursday 20 August 2015

Leica Photogrammetry Suite - a.k.a. - Imagine Photgrammetry

ERDAS Imagine now has Leica Photogrammetry Suite incorporated. It has been rebranded as, "Imagine Photogrammetry" or so I understand. This may also have done the job for calculating distortion coefficients that I mentioned in my previous post but I did not get around to exploring it properly. I would like to experiment with satellite stereo imaging, like SPOT, Pleiades, etc. I may also use it to validate the results from OpenCV and it vould be a potential low cost option for creating orthomosaics with UAS imagery, as we already have an ERDAS licence at the University.



An alternative option is VisualSFM, a different software package I am looking at after a reccomendation from a UAV operator last week- but that will be a post for another day.

Wednesday 19 August 2015

Camera calibration and distortion coefficients

Some cameras you might get and would like to use for photogrammetry come with all the required info in manuals, metafiles or have already been calibrated by someone else. But what happens if you are missing something? Focal length, etc is relatively easy to get but the lens distortions (radial, tangential) are not. We had an aerial survey coming up and needed to get a camera calibrated ASAP. When you search online expect to get out of your depth rapidly in matrices and formulae. But then if you are lucky you might stumble on OpenCV. 




OpenCV is an open source computer vision and machine learning library which has what you need to calculate the distortion coefficients. As usual the most complicated thing is getting the software to install, run or compile so I ended up pulling what I needed out and running it in Python separately. In theory it seems to work and finally I have a legitimate reason for having a chessboard up on my monitor. It also means I can start trying to find the other values I need for the camera.





Edit: That is not me, my office or my computer!

Friday 14 August 2015

Flight mode

We have recently acquired a 3DR Solo - a 'use out of the box' class of UAV. It is very stable and manoeuvrable. Additionally, you just need to attach your phone to the controller and it becomes your video display for piloting the platform so that cuts down on hardware costs.


I heard a funny story today from someone who had been piloting a similar UAV at the max line-of-sight range and therefore completely reliant on this video link, when suddenly their wife rings in and the video link switches to the 'incoming call' screen. One to watch out for....

Setting the phone to 'flight mode' would solve the problem but that is definitely not the 'flight mode' they had in mind when building those features into phones!

Monday 10 August 2015

Dublin Bay - Landsat 8

After I posted recently about the Dublin Bay biosphere I thought I should follow up with a quick post on using remote sensing for the same area. Here is a beautiful Landsat 8 image of Dublin Bay and the oceanic processes in the area are easy to see. I'm no oceanographer or marine biologist and so I have no idea if it is sediment, algae, plankton or a combination of all 3 but it certainly looks nice. Unfortunately the problem is that I'm trying to find an image where this is minimised and I have gone back as far as 2013 (which is around when L8 started provided imagery from) and it is evident in all of them.


Thursday 6 August 2015

It's mine!!

I'm not convinced that having the, 'claim authorship' button beside the 'download publication' button is such a good idea....Good job RG design team.



Tuesday 4 August 2015

Dublin Bay - UNESCO Biosphere

A UNESCO Biosophere designation has been extended to cover the whole of Dublin bay, not just the Bull Island - approximately 300 square kilometres. The announcement is available here at the RTE website. Having gone to school just up the road from here and spent lots of my childhood visiting grandparents beside the Bull Wall, I am very glad to hear it is being taken care of.



I was originally not sure what spatial extents they have assigned to the Biosphere - some of the imagery seems to imply that its limits were the entrance to the Liffey, south to Dun Laoghaire Harbour and North to the Bull Island, but certainly the Lord Mayor makes reference to Malahide as well in a number of press releases. I found a better map online that defines it fully.



It seems to have three zones, but four colours? It could just be the transparent yellow layer clashing with the underlying blue sea layer in the GIS. The core zone covers the inner bay and entrance to the Liffey, the coast at Howth and the wetlands/shore at Donabate. All beautiful areas that I have spent plenty of time over the years. It does not seem to extend North past Portmarnock so I do not think Malahide or the entrance to the Broadmeadow estuary is included.

The Dublin coast is particularly relevant to a number of projects I have been involved with:


  • I worked as a surveyor and GIS Analyst in a Dublin County Council for 4 years.
  • After I joined the NCG we carried out Mobile Mapping System LiDAR and imagery road surveys in the Port Tunnel and surrounding areas. 
  • We performed some coastal erosion surveys using UAVs in Portrane in early 2012
  • Tested photogrammetric methods to assess UAV accuracy during matching in featureless terrain along the Portmarnock beaches.
  • Dublin bay and the Bull Wall was the test bed for the early satellite bathymetry study which lead to the SFI Fellowship.  

Looks like there might be many more opportunities for non-invasive, non-contact survey methodologies (i,e. remote sensing and photogrammetry!!) to prove their worth in this area over the coming years.

About Me

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My name is Conor. I am a Lecturer at the Department of Geography at Maynooth University. These few lines will (hopefully) chart my progress through academia and the world of research.