Gerard Toonstra's Blog (31)

Opensourcing ESC work

So almost a year ago, I posted about how I started work on a field oriented control ESC:

Redesigning multirotor ESC's

Some people in the comments already said how they made their own or started work on different ESC's. I went through 5 iterations of the ESC after the…


Added by Gerard Toonstra on July 12, 2015 at 6:00am — 12 Comments

Experiments with an industrial USB webcam

Above is a fullsize image of a 5MP webcam. A webcam usually has a CMOS sensor and commercial ones support up to 720p resolution. 720p is a result of the usb bus bandwidth available to stream the images and since many computers still use USB 2.0, this is the maximum resolution for reasonable framerates of 25fps or so. At USB 3.0 you can achieve 30fps with uncompressed data, or…


Added by Gerard Toonstra on July 3, 2015 at 3:51pm — 6 Comments

Project Ion charter

I'd like to invite the diydrones members to participate in a project I started on github: Project Ion on github

The control of uav's have improved a whole lot in the past couple of years and you can now pretty much put one in the air and wait for the results to come back, whether these are videos…


Added by Gerard Toonstra on June 7, 2015 at 1:57pm — 8 Comments

Cheap 1-2cm (scale) accuracy for your surveys

Image: Topcon RTK collecting survey points

High precision GPS systems are getting more known and used and RTK is already becoming a familiar acronym. This post is about the use of RTK for collecting ground control points to be used in high quality survey results, not about RTK for navigation use (that's a lot harder). What I was looking for is…


Added by Gerard Toonstra on April 21, 2015 at 7:46pm — 54 Comments

Work domain analysis and cognitive systems

I used to work as humble research engineer/scientific developer for a research lab in the Netherlands. It's how I got into this business eventually. In that environment I also got introduced into the various topics related to cognitive science, interface design, cognitive workload, work domain analysis and how this work typically generates complicated technological requirements…


Added by Gerard Toonstra on February 11, 2015 at 7:00pm — No Comments

Ground station survey results

It's been a week that the ground station survey is online and it received 82 responses. Not a whole lot for a forum like diydrones, but most companies only manage to interview 5-10 people. So the results of this survey should be considered a valuable resource.

In this analysis, I won't highlight the points that seem inconclusive, because they didn't get convincing…


Added by Gerard Toonstra on February 1, 2015 at 5:36pm — 10 Comments

Ground station survey

Ground stations are the means you have available in the field to interact with your autonomous vehicle, so they're a very important part of the toolset to conduct your work or hobby. The ground station as we know it now is not just there to support your activities to plan or execute the flight, they also contain functions for initial setups,…


Added by Gerard Toonstra on January 26, 2015 at 7:12am — 3 Comments

Multirotor testing device first prototype

This is a tryout prototype of a multirotor testing device. Someone else built it for me actually who normally works with doors and heavier stuff, so it got bulky in the end and the rings gain too much momentum to be anything comparable to a multirotor this size. All connection points are regular bearings: inner ring is roll, second ring is pitch and third ring is yaw.…


Added by Gerard Toonstra on January 17, 2015 at 6:00am — 2 Comments

Lumix CM1 camera, a step up in quality for surveys?

This camera may be able to improve the quality of shots taken from drones for those jobs where you need the ultimate in precision and texture quality ( I think? ). This is, according to the manufacturer, a camera with smartphone capabilities. It has a Leica Lens, 1" sensor and takes 20MP photos and will go for $1,000 in the US. It weighs 206g, so slightly more than a Canon. I…


Added by Gerard Toonstra on January 6, 2015 at 11:49am — 25 Comments

Redesigning multirotor ESC's

It's been quiet on my front, but that was because I was redesigning ESC's (for multirotors and AP's).

Most of the ESC's for multirotor use the SimonK firmware on a relatively simple Atmel microcontroller. There's a single control wire running from the autopilot to the ESC, which is a signal proportionally dictates how long the mosfets are left open and as such…


Added by Gerard Toonstra on October 21, 2014 at 6:18am — 88 Comments

From survey to visualization

So I had some time to look into the 3D reconstruction and visualization some more and managed to make significant improvements to the workflow. In the first results I didn't clean up points and applied the texture to the entire model in one go, straight from generation -> blender. This makes the UV atlas ( a parametrized texture, where it decides which surface gets…


Added by Gerard Toonstra on July 16, 2014 at 6:25pm — 10 Comments

3D rendering of an area taken in nadir view

This is a short animation of the quality you should expect from about 220 images in nadir view over a 100x200 area. The texture is a single UV atlas of 8192 and at this size a little bit stretched when it comes to detail. Nevertheless, the mesh detail itself is very reasonably, showing humps and bumps of grass overgrowing the sides and areas with dead leaf and…


Added by Gerard Toonstra on July 13, 2014 at 5:30pm — 14 Comments

Point cloud densification and orthophoto generation

This is a continuation of previous blog posts about how 3D reconstructions work. In this image you see a dense reconstruction of the same data set used before. I removed…


Added by Gerard Toonstra on April 24, 2014 at 5:20am — 7 Comments

The European Commission has today proposed to set tough new standards to regulate the operations of civil drones

The European Commission has today proposed to set tough new standards to regulate the operations of civil drones (or "remotely piloted aircraft sytems" – RPAS). The new standards will cover safety, security, privacy, data protection, insurance and liability. The aim is to allow European industry to become a global leader in the market for this…


Added by Gerard Toonstra on April 8, 2014 at 10:00am — 33 Comments

Accuracy evaluation: is better than 5cm possible with uav's?

We did a quick evaluation how much accuracy we could achieve on all axises using a multirotor. We read many accuracy reports from fixed wings and this teaches us that the planimetric accuracy (horizontal) is usually about 1x the ground sampling distance (GSD) (0.5 if you're really good and have better cameras) and that the vertical accuracy (Z) is usually 2-3 times the…


Added by Gerard Toonstra on April 2, 2014 at 6:43am — 24 Comments

From twoview to a complete sparse 3D point cloud

Continuing on from the last post on this subject, here's a complete sparse point cloud generated from some 40 images. In the twoview case it became apparent that you can triangulate points from 2 images. In a two-view match you sometimes get inaccurate or incorrect matches, which…


Added by Gerard Toonstra on March 28, 2014 at 4:49pm — No Comments

A twoview 3D reconstruction

Click for big!

In the last post just two days ago, I talked about the fundamental matrix and a homography which allowed 2D images to be warped in such a way that they overlap. That technique works a bit better if you take the photos from the same…


Added by Gerard Toonstra on March 23, 2014 at 6:11pm — 4 Comments

2D image post-processing techniques and algorithms

A number of people on this site are using their vehicles for aerial mapping. There are tools available for image stitching, which basically produces a rough idea about what the terrain looks like from above. Image stitching does not compensate for perspective and usually contains lots of artifacts. The reason why some older tools don't really work that well is because they rely…


Added by Gerard Toonstra on March 21, 2014 at 8:41pm — 4 Comments

Autonomous path planning for robots with blender

Here's a couple of screenshots of a little experiment I did today. This is a slightly reduced mesh from the point cloud example yesterday. In this work I'm using the blender game engine for path planning of an autonomous robot. My "robot" is that green cube over there and it's trying to get to the purple sphere. I'm using a navigation mesh laid over the parts where I don't want…


Added by Gerard Toonstra on March 5, 2014 at 8:21pm — 4 Comments

Making a 3D SBS video from a set of 2D images

In a previous post on diydrones I showed how to make a mesh model for visualization or games from a landscape surveyed by a drone. That workflow started off with the set of bare 2D images and used VisualSfM and CMPMVS to generate the point cloud and…


Added by Gerard Toonstra on March 4, 2014 at 2:30pm — 3 Comments


Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

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