After waiting for a lot of cloudy, miserable days to pass, I finally got to fly my new TBS Caipirinha today. This is my first flying wing that I’ve managed to fly. I do have an RVJet but that is much more intimidating, it’s huge compared to this.
Launching the TBS Caipirinha was really easy. I just held it by the wing and gently flung is like a discus with about half throttle. With both hands on the TX I full throttled it and the wing flew straight up, vertically, into the air. This bird climbs really fast. I’m used to flying EasyStars, AXNs and Bixlers, which fly great but take a while to reach altitude, and sometimes struggle to get into the air when there’s no headwind.
There was hardly any wind today. In fact the wind was so gentle I didn’t even bother to land upwind as I thought it would make no difference. The Caipirinha didn’t seem to care about the lack of head wind for extra lift on take-off, it’s like it wants to soar high as quickly as possible.
There is no rudder, which takes a bit of getting used to if you normally have one, but it’s a total doddle to fly. It’s also very easy to land. If you cut the powers it sort of drops but stays flat, so if you judge it right you can land in a pretty small space. With my EasyStar I often find myself going around again because the bugger doesn’t want to land in the same field as me!
I’m also using the new FY41AP Lite, which is totally awesome. It’s an autopilot, with Return to Launch, Auto Balance Mode and Loiter Mode and has an On Screen Display all built into the same unit. Plus it is tonnes cheaper than the full FY41AP, which has waypoint capabilities, which I have never used thus far on a plane.
When I next test this plane I think I want to try fitting a point and shoot camera, with the lens pointing straight down through a hole in the front of the wing, to see if it will carry it and take some amazing photographs.
I’ve recently become a little obsesses with making 3D geo-referenced models from my aerial photographs and thought I’d write a short blog post on how to go about it if you want to give it a try.
You will need:
1. An aerial platform, fixed wing or multirotor (i.e. RC plane, quadcopter or hexacopter etc)
2. A camera that can be triggered remotely or has a time lapse feature, such as a Canon DSLR with remote shutter switch or Gentled trigger or any of the Gopro cameras.
3. A GPS Data Logger, unless your camera has the ability to tag images already.
4. Software to extract the GPS coordinates and height data from your GPS logger and match up the data to your photographs.
5. Software to create your 3D model. Potentially the most expensive element, though there is a free option for hobbyists. Read on to find out more.
Geotagging and Modelling List in detail
Any aerial platform with do really, so long as it can carry the camera you want to use. A cheap option would be an EasyStar II or Bixler II plane, or say a DJI Phantom quadcopter. These are good options to use with a Gorpo. For larger cameras you will obviously need larger machines. Either way you want your camera to be able to point down at 45 degrees, or you can get away with straight down on a wide angle lens. For better models you may want to do both, a run with camera pointing straight down and another with the camera at 45 degrees. You may have to make a special little rig on a plane for this as it will be better for the camera to be underneath, though with the right weight distribution you may be able to hang a Gorpro over the nose at the front. However you do it you don’t want any of your plane or quadcopter in the shot.
Next you need a GPS data logger that records coordinates and elevation, or height, at regular intervals. Some are better than others. I’ve tried three so far and I’m particularly liking the Holux M-1000C at the moment, which starts logging pretty quickly and reasonably accurately too. Note: for making 3D models with some software you don’t strictly need the GPS information. Agisoft, which I’ll mention again further along, for example can make models just from images, but the process is a lot quicker if you supply it geotagged images – plus you can use your images/model in Google Earth Pro and high end software if you geotag your images. Anyway, assuming you are geotagging, you need a device like the Holux which you can attach to the top of your plane or quadcopter. With the Holux you simply switch it on and an orange GPS light comes on solid, then starts blinking to indicate it has found the required amount of satellites and started logging information, after which you simply leave it until you’ve finished then switch it off. You then download the logs via a USB cable to your computer.
After this you may need a free program called GPSBable which can interpret the logs from a whole list of devices and turn them into useful GPS data, .gpx files. After that you can use another free program called GPicSync to synch up your photos with your GPS data. This is done by utilizing the time-stamp created by your camera and matching up the times from your GPS logger, which is made easier if you match up the clocks in both devices beforehand. However GPicSync does let you input the time difference between the two if you didn’t do that.
Cameras that Geotag for you
First of all I will say you can skip the whole GPS logger bit by using a camera that tags your photos for you. This will save you a whole heap of work and bother. However, there still aren’t that many cameras around that will do this for you in a useable fashion. I had a lot of trouble finding one and ended up using the GPS Logger route instead, which is what most people are doing. There are point and shoot cameras that geotag, but they either don’t tag the elevation for you or don’t have a time lapse function or the time lapse function isn’t frequent enough or their GPS logging isn’t accurate and/or regular enough. You could rig up some kind of servo action to trigger the camera button old-school style if there is no time lapse function or it’s too slow, like every 10 seconds, if you find a camera that is otherwise good for the job..
At the time of writing the Ricoh WG-4 GPS looks like a promising light weight camera, I will be trying this one sooner or later if you want to wait and see how well it works. Also the Canon 6D had built in GPS and is actually quite cheap for what it is for pro users. The Canon 6D has a few shortcoming for photographers so it’s actually pretty cheap compared to the 5D MKIII. Most of the shortcomings, like lack of cross type focus points and slightly smaller than 100% viewfinder are totally irrelevant to aerial photography so it could well be a good buy for people like us. It also has more plastic around the top instead of metal, which some people say makes it feel cheaper but I think is actually so the GPS antenna can get a better fix. There is also the GPS Receiver GP-E2, which is compatible with the Canon 5D MKIII and 6D (Not 5D MK II though) that fits onto the hot shoe. You might wonder why you’d need one on a 6D if it’s already built in? Well, you might not! However, I have wondered if that big old hexacopter and all its gubbins might block the GPS signal from getting to the camera all the way underneath your rig… if it did you could buy a hot shoe/flash extension cable and mount the GP-E2 up top.
So, however you figured out your camera/GPS setup, the next step is the flight and taking the photos. If you’re taking images of a building to make a 3D model, you basically want to fly at a height about 20 meters higher than the top of the building and try and stay around the same height for every photograph. Fly at the building from all four sides, one side at a time, with your camera pointing down at 45 degrees and make sure there is around a 50% overlap in the cameras field of view. In the diagram (Fig.1) the blue box is your building, and the red dots represent the spots where you take a photo from on each side. The yellow lines represent the field of view for your camera lens, note how each image will overlap. Don’t worry, it doesn’t have to be exact so long as they overlap you will capture all the needed information.
If you’re flying a quadcopter and triggering the camera yourself, you can literally stop at each red dot and take a photo and repeat the process for each side of the building. If you have a time lapse set to every 1 second you can just fly steadily along the blue lines facing the building and repeat for all sides. If you’re flying a plane you can fly in from one side, turn around and do the other side and scan up and down until you’ve covered all sides. For more detail you can do some straight down shots if you like, and even some straight on shots from the ground, but you don’t have to do that. You can use the same method to map hills or mountains and valleys, though these will probably be better achieved with a plane than a quadcopter in some cases where you’ll get longer flight times. Once you have your photos, if they’re not already geatagged by your camera, you need to do the synching process mentioned above.
With some machines you can do your flights autonomously, even triggering the camera for you at given places, but this article is mostly for people starting out, who want to give it a go and not blow $20,000 or more just yet.
3D Modelling Software
The final stage is to load your geotagged (or not) images into some software to make your models. The prices for the software start from mostly free with Autodesk123D (with paid for upgrades), where the photos don’t have to be geotagged, to the moderate standard version on Agisoft Photoscan at $179, to the pocket-squeezing full version at £4499 to the eye-watering 5000 euros for Smart3DCapture and 6500 euros for Pix4D (rental options are available). There are others, but they’re really expensive and I don’t want to give anyone a heart attack, if you haven’t had one already.
So a few weeks back we had a go at flying out DJI S800 Evo autonomously, then flew up and down over a haystack with an aim to modeling it.
Here is the model on a PDF (download to your computer, just clicking the link won’t work): haystack – created using Agisoft Photoscanner Standard Edition. If the PDF shows blank you need to update Adobe Reader to the latest version.
Here is the video of us bimbling about to get the haystack photos:
If you've seen my aerial photography pages you will notice there are rather a lot of DJI Wookong videos, this is because I'm totally addicted to them. So much so I've decided to make a new little website just for DJI flight controllers with tips for other potential DJI addicts.