We use the BlueROV we purchased in Aug 2019 for surveys. We’d like to have use it to create some habitat maps. We’ve got access to Pix4D to create DEMs, so ideally we’d like the videos we’re taking to be georeferenced. My initial thinking was that the Waterlinked GPS add on would be suitable, but with the DVL being purchasable from the store, would that be able to do the same job?
Any tips appreciated,
Different device types are useful for different purposes. A DVL is often more precise than a USBL / UGPS, but needs its initial position set manually/externally, and loses its accuracy over time due to integration error, so the readings will start to drift if the vehicle is submerged for an extended period without corrections from an absolute/external reference (like some form of GPS system).
Depending on what kind of deployments you’re planning to do, either device could be suitable. From your current description it’s not clear which would be best.
Thanks very much for the reply. Sorry for the delay, this got temporarily put on the backburner.
When you say it drifts over extended periods, what time periods are you talking about? Minutes? Hours? I think we’d be using the topside map as a guide anyway, and post-processing the footage, then georeferencing it that way.
Just to confirm the DVL would be suitable for the BlueROV2 we have? It was purchased Aug 2019.
Hi Dean !
Not sure how relevant it is, but I’ve had some success generating maps with the free photogrammetry tool WebODM, and video recordings directly from the ROV camera. These take awhile to process, but no position reference is required! I’ve only tried small sections of reef thus far…
As for a DVL on your ROV, I would recommend updating it to use BlueOS, if you haven’t done so already. Getting the DVL setup with the extension is potentially less painful then dealing with the older Companion OS.
Thanks Tony, much appreciated. We’ve got a guy here who agrees that you don’t need position to create the maps, but it makes it easier to make sure you’re getting good overlap? It’s more about efficiency of battery usage and time I gather.
For sure! Their is much less processing required if you can tell the tool the position of the camera, its angle, and what direction it is facing. The DVL, even with drift, should be more than adequate to navigate for photogrammetry /overlap purposes.