BritishIdeas
Interesting Tech Projects
Astrophotography and CHDK
Jun 7th
CHDK is an alternative firmware for many Canon cameras, particularly point and shoot and I previously wrote about it here. One of the nice features is the ability to take continuous pictures for long periods, which makes taking photographs of the night sky possible with a low cost camera.
Here are my first experiments to see what is possible. I am fortunate to live in a place where the light pollution isn’t so bad and there are over 300 sunny days a year.
I set my Canon A480 up to take continuous 30 second exposures pointing roughly north, around 45 degrees above the horizon. I left it for about one and a half hours, during which time it took 155 pictures. I used ISO 80 and the auto focus set to infinity. More >
CHDK and Canon A480 Quick Start Guide
Jun 3rd
CHDK is an alternative firmware for some Canon cameras. It provides access to lots of cool features that are found only on high end SLR cameras, plus some features that are not found anywhere.
Why the Canon A480? Because refurbished cameras are available for $75 from Adorama with a one year warranty and only one version of firmware has been seen on them to date. This means that there is a very good chance the firmware in the A480 you receive will be compatible with CHDK.
This short guide shows how to quickly access some useful features. It is not intended to be exhaustive or replace the CHDK wiki or forums.
CHDK can be set to automatically load when the camera is turned on, however I don’t use that feature because I want to use an 8Gb SD memory card. Cards of 8Gb create complications when autoloading CHDK, but I want the extra space for long time lapse photography.
Download and extract the A480 “full” CHDK zip file from the CHDK website. Extract the files to the top level of your SD card and put the card into your camera. More >
You Tube, H.264, High Definition and FFmpeg
Jun 3rd
Recently I had the need to take a set of jpeg images and convert them into a high definition time lapse video, then upload to You Tube. Easier said than done…
To get the best quality I wanted to use H.264/MP4, which is also recommended by You Tube. I also wanted 1080P. The problem is that You Tube doesn’t seem to like B-frames in the file, and messes up the start of videos. So here is the solution I found.
Firstly I needed to upgrade my Debian server to Squeeze.
Next I compiled x264 and FFmpeg as described in How To Build FFmpeg on Debian Squeeze.
Finally I ran the following FFmpeg command line to generate a time lapse video at 24 frames per second (-r 24), using 1080P (-s hd1080) with no B-frames (-bf 0):
ffmpeg -r 24 -i %04d.jpg -s hd1080 -vcodec libx264 -vpre hq -bf 0 -crf 16 myfile.mp4
It’s important that the frame rate is specified before the input source in order to make FFmpeg apply the frame rate to the source. Note that trying to use qt-faststart causes You Tube to complain about the audio, even though there isn’t any audio.
Crazy Flight Paths
Apr 20th
This is the flight path of British Airways BA84 on April 20th 2010 flying from Vancouver to London Heathrow (from FlightRadar24.com):
British Airways BA84
What happened?
- The flight (Boeing 747) took off from Vancouver while Heathrow was still closed because of ash from the Eyjafjallajokull volcano in Iceland. When it reached the Isle of Man Heathrow was still closed so it was put into a holding pattern for a couple of hours at cruising altitude.
- Other British Airways flights were being diverted to Shannon, Ireland and it looks like the airline and/or ATC gave up and sent the aircraft there, at which point it started descent to 26,000 feet.
- The British Government announced that at 10pm all UK airports would reopen. BA84 then turned back towards Heathrow while over Dublin.
- When the flight reached Birmingham it was put back into a holding pattern, probably because it would have reached Heathrow too early.
- The flight landed at Heathrow at around 9:45pm
Not a flight I would have liked to have been on!
Compiling OpenScales 1.1 with FlashDevelop 3
Feb 7th
This article describes how to compile the OpenScales mapping library for Flash in FlashDevelop 3. OpenScales is an open source LGPL library for displaying interactive maps using Flex and Actionscript. It has many of the features of OpenLayers. FlashDevelop 3 is a free Flash development environment and can be used with the Flex SDK from Adobe.
This article assumes you already have the Flex 3 SDK and FlashDevelop 3 installed and working. See my post from two years ago for help. More >
Rendering of a CNC Machine
Dec 29th
In preparation for a long term project I am working on I created a 3D model of a 3-axis CNC machine in Google Sketchup and rendered it in Kerkythea.
This took quite a bit of tweaking to get exactly the look that I wanted, which is the appearance of the CNC machine inside a large light tent, reducing shadows and a distracting background. I.e. the typical look used for product photos.
CNC Machine
Mechanics of a CNC Machine
Improved End Mill Rendering
Dec 17th
I played around with my Sketchup model a bit and vastly improved the flutes on the end mills. Here is a Kerkythea render
Google Sketchup and Kerkythea – A Perfect Combination
Dec 12th
Google Sketchup is pretty nice. I’ve tried 3D CAD programs in the past but never really invested the time to climb the steep (for me) learning curve. There was a bit of a learning curve with Sketchup, but once I got into the “right” way of thinking it became easy to use. Now I use Sketchup all the time, from drawing diagrams for my CNC hobby, to modeling home projects.
The one problem with Google Sketchup is, well, the output looks like a sketch. But now I’ve found a free renderer that not only has a plugin for Google Sketchup, but is just as easy to use as Sketchup. It’s called Kerkythea.
Install, run, and follow the quick start tutorial and you will be rendering your Sketchup models in less than a hour.
I recently decided to try and model and render some sprial up-cut and down-cut end mills in Sketchup. The results are below.
Spiral Up-cut End Mill
Set of Three End Mills on a Stainless Steel Surface
Ridgid R2400 Router
Dec 10th
I have made Christmas presents for this year, so now it’s time for some upgrades to my CNC machine. The first upgrade is to replace my poor Dremel with a small router.
Small palm routers or laminate routers are typically around 3lb in weight, which is small enough to fit on my hobby CNC machine. I liked the DeWalt laminate trimmer, but it doesn’t have variable speed built in. Next choice was the Bosch Colt, but I have heard some stories of how several hours of use can melt the plastic around the bearings, ruining them. My final selection was the Ridgid R2400 laminate router. Nothing but praise and easy to mount.
Note that the R2401 is quite different (and heavier) than the R2400. It seems that places like Home Depot and Lowes now stock the R2401 instead of the R2400.
A big reason for replacing the Dremel with a router is better performance under load and larger shank size. Larger bit = faster and deeper cutting. My Dremel has run for probably over 130 hours on my CNC machine and it’s showing the signs. It can still cut accurately but there is now a problem with the power, and it is starting to become a bit unreliable.
The first problem is how to mount the R2400 to my CNC machine. The solution I came up with is to press my Dremel into service one last time to cut some 1/4″ MDF. I will sandwich the parts together to create a holder that is 1″ thick with a back plate of 1/2″
The design was done in Google Sketchup:
I then rendered it in Kerkythea for fun:
Now to start cutting…
