Orthophotos are truly wonderful things. Derived from photogrammetry they deliver a level of detail and recording at resolutions beyond the average camera can create on their own. Being able to record a site at 1mm per pixel or less delivers art and accuracy in a single frame. Being able to measure with confidence things on the seabed from the comfort of the office is priceless.
But there is a downside. File sizes tend to be massive and compact area like the P47-D crash site ends up generating a 1.67Gb TIFF file. Viewing that online is going to stretch the broadband a little…and we are still waiting for 5G.
Big File? No Problem
Necessity is the mother of invention. And if not invention its a good motivator to look around to see if anyone else has solved the problem…it was another project for a client (not underwater for once) demanding not only accuracy but being able to securely view and measure orthophotos that triggered some very kind and clever folks at Drone Lab to get in touch. They were delivering orthophotos to clients online and in a web browser…would I be interested in having a look-see?
The Scapa Torpedo Site
At 215Mb the Scapa torpedo orthophoto was a good first test. Resting in 30m of water this torpedo was destroyed in a controlled explosion not long after it was digitally preserved. There are two versions of this orthophoto; one with relative accuracy (scaled and anything in the scene accurate, but location unknown) and a second version with absolute accuracy (scaled from GIS data). The relative accuracy version is good enough to prove its a 21″ variant, and the absolute accuracy version is good enough to locate where the parts are in the context of the rest of the planet.
There are basic navigation tools and its best viewed in full screen mode…but either way you can zoom in and count the glass bottles on the seabed, if thats your thing.
This orthophoto is the one with relative accuracy so for now the online viewing tool doesn’t understand the scale of 1mm per pixel so measurement is not available…but thats already an enhancement request.
The SS Thistlegorm
Two years ago we scanned the wreck of the SS Thistlegorm. Viewing the 3D output has been available on platforms like Sketchfab:
But the detail in the orthophoto will typically be far higher. Add in GIS/location information and not only can the ultra high resolution orthophoto be viewed, but direct measurements taken.
At 2.68Gb the lower cargo deck, complete with its cargo of fuel bowsers, rifles, wellington boots, lorries and motorbikes, is a massive file. But now it can be viewed at its native resolution of 1mm per pixel:
Check out the schooling fish in the lower right corner…unlike pure photogrammetry that won’t cope with movement the orthophoto will freeze the fish in time.
Conclusions? There are other ways of sharing and viewing orthophotos but for sheer convenience, ease of use and security Dronelabs have a really neat tool for delivering massive detail on any device, including your phone.
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