Lasers, sensors, cameras! A 3D scanning backpack for UC Berkeley (part 1)

Lasers, sensors, cameras! A 3D scanning backpack for UC Berkeley (part 1)

About a year ago I was contacted by a professor at UC Berkeley who had found my resume online. Her team had produced a backpack device that was capable of collecting data to generate 3D models of internal spaces, and she needed a new backpack designed that would be smaller and lighter. I took this on as a part time project while I was looking for full time work, and it was a fun challenge. I’ve talked about this project in the past, but they finally went live with the backpack so I thought it was time for a post.

You can read all about Professor Zakhor’s original backpack on the EECS website. This is what they had before I arrived. It weighs over 70 pounds, is built to hold an changing array of sensors and cameras, and I understand that it went through many iterations and changes as they developed the software techniques that could turn the data into usable 3D representations of internal spaces. My job was to provide a compact, lightweight platform that provided stable and well defined positions for a suite of sensors. Many of the sensors needed to be adjusted to different angles to accommodate users of different heights, or movement through different environments.

The sensors on the version of the backpack that I designed include:

That’s it for now, but it’s possible to attach other pieces as needed. I sourced an embedded PC that seems to have the processing power to shove all the data from those sensors into some SSDs, and the entire collection of parts is powered by several lithium ion batteries. The batteries are an off the shelf solution, and have a good amount of intelligence and safety built in. We run the batteries in series to create a voltage from about 18 to 60 volts, and a DC-DC converter regulates this to a main system voltage of 24 volts.

Here’s a creepy render of the system on a mannequin.


Check back soon, and I should have an explanation of what each of the sensors is doing, and how I designed this thing!


Bike tour 2013, the rest of it!

Bike tour 2013, the rest of it!

One of the big differences between doing a solo bike tour and riding with friends is that when you’re not riding it seems like a lot more fun to socialize with everybody than it is to isolate yourself with a cell phone writing blog posts. Especially with a truck to move us along and coordinated meals, there was a lot less time to just sit around blogging.

Of course that doesn’t stop me from taking pictures along the way, so here are some of those!

This is one of the bridges that we crossed, and if I remember right we were able to zoom over it quite quickly.

As always, the California coast is gorgeous.


We had to stay lotioned to avoid burns.

I thought this irrigation pond was cool.

We had to cut through a field full of vegetables, and some rubber bands had spilled out onto the ground.

This is what it looked like for a while. I was glad to have far tires.

This is how I imagine touring across the Midwest looks.

Hey, free rubber bands.

Comically large taco salad.

We need all this food for energy.

This was out only link to the outside world in Big Sur. Oh, and the wifi once we got the password.


Some people have no respect!

The aftermath of not enough lotion. 90% of that was one morning before lunch.

That’s all for now! We camped three nights and did around 150ish miles, and I think I learned a lot about touring with friends. It’s fun in a different way, but still a blast!

Snap away!

Snap away!

I see that I haven’t posted any new projects since February, but I’ve definitely been keeping busy!

Just before my last photo post I flew up to Washington and did some photography for my friend Molly, shooting her bikini project.  Check it out!

Just before that I shot Oakland Nights… Live! on a BART train, and then right after that I flew to Wisconsin for Thanksgiving with my family. In February I scouted out a “post apocalyptic folk drone-core doom” band by the name of Feral Booty, in March I shot a power soccer match in Berkeley, and also Oakland Night… Live! in their new location!

All of these photo sessions felt like a pretty steady progression from what I’ve been up to (though flying to Washington for a project was special and out of the norm!), but things have recently started to intensify even more. In late March I got a text about a super secret event in an undisclosed location, and boy was it something! Check it out- and if you have a Flickr account and your settings adjusted for it, you’ll even see some ‘adult’ content. Some folks had taken over an old disused movie theater, and the show on stage was very “anything goes”. Very exciting!

I had one more ONL show since then, but then this week something kind of special happened. I was walking home from work, taking a different route than usual when I saw a car across from the post office that had been absolutely covered in bird poop. A family of herons had made its home up there, and somebody parked under them for a few weeks. I took an Instagram picture and got a good reaction from my friends and family:

shitty car

It was cool, but I felt like I could do better if I had the right light and a better camera. I looked up this website to see what direction light would be coming from at different times of the day (, and saw that walking there before work would make the light come in from the front of the car, the side by the sidewalk, so that was maybe as good as it was going to get- specifically really darned early so that light would have some good directionality and color. I decided that since the car could get towed any time there was no time like the present. I said, “I totally should!!” and set my alarm. It was really hard to get out of bed at dawn, but then I reminded myself, I TOTALLY SHOULD TAKE THAT PICTURE!!!

It didn’t really make me less tired, but it was enough to get me out the door.

I was borrowing a super wide angle lens from UC Berkeley, and so I brought that along and took this picture, which I posted on When I went to bed a couple of dozen people had upvoted it, and there was no count on how many had seen it. When I woke up it had made the front page, and over 200,000 people had seen it. Now, in less than a day nearly three quarters of a million people have seen my picture!! This is the most exposure, by far, that any of my images has ever had, and I’m totally psyched.

many views

DNA thumb drives: How we’ll store holographic videos of cute cats in 2030.

DNA thumb drives: How we’ll store holographic videos of cute cats in 2030.

I was reading the news today, and I came across an article that researchers have proven the ability to store 700 terabytes of data in a gram of DNA.

This is amazing! I do not think that anybody as recently as twenty five years ago would have dreamed of where this is going. Back in 1990 the Human Genome Project set out to begin sequencing the entire human genome. It wasn’t until 1995 that a genome had been sequenced- only a bacterial genome much smaller than ours! Finally in 2003, after spending $3 billion the human genome had been sequenced by the NIH project. Some people did have an idea that gene sequencing could be done more quickly and efficiently, and Celera Genomics set out to race the Human Genome Project and sequence the genome first. At a cost of only $300 million, Celera was able to reach a draft sequence in January of 2000.

It’s not surprising that a private company taking some risks could beat a government program on cost and speed, but what is really amazing is that the drop in price didn’t slow down- it sped up. Recently it sped up a lot. For nearly a decade the cost of sequencing a given number of base pairs of DNA was falling at about the same speed as the cost of putting transistors onto microchips, improving at the same rate as Moore’s Law. In early 2008, a new generation of gene sequencers was introduced, and then things went nuts.

Today it is now possible to have your entire genome- your personal genome- sequenced for as little as $4,000, and it can be done as quickly as twenty seven hours. That’s on Illumina equipment, and they have many competitors working to unseat them with new techniques. Regardless of whether those techniques come along this year or next, I have heard talks given where folks who know the workings of the Illumina systems are willing to say that they are able to squeeze more performance and lower cost out of their existing technology with fairly boring incremental improvements, and most people in the business recognize that the $1,000 genome is just around the corner, and the $100 genome is not a crazy idea.

Probably the coolest part of all of this is what it could mean for medicine. The ability to quickly and cheaply read somebody’s entire genome would make it far easier to test for genetic diseases. Today you have to suspect a particular disease and order a test that targets just that chromosome. I once had a blood test to determine whether or not I was a carrier for Spinal Muscular Atrophy.  The geneticist ordered a test to detect the most common mutation of a specific gene to see if I was a carrier. Under certain circumstances I would have been referred for a second test that would do more extensive sequencing of my copies of of genes that produce survival motor neuron protein. These tests will not tell me anything else about my health or what I may or may not pass on to offspring.

When whole-genome diagnostic sequencing becomes common, then it will be possible to say “While we’re looking at your DNA, lets go ahead and see if you’re a carrier for anything else.. or if you’re pre-symptomatic with anything serious”. There are certainly ethical issues when it comes to messing around with our genes, but how much could it improve our quality of life when we can learn ten years before symptoms that we’re likely to be quite ill by the age of 40 with some rare disorder? What if we can devise personalized approaches that can nip the disease in the bud and let us live long and healthy lives? This could mean either chemical drugs or therapeutic insertion of genes into our living cells to change our genetic fate. My only hope is that if such things become possible, the prices will continue to drop at an extraordinary pace so that these treatments do not remain a privilege of the super rich.

Saving lives and improving quality of life is great, but I mentioned holographic videos of cats earlier and I don’t want to disappoint anybody. As the article about the Harvard team said, we are now able to store 700 terabytes of data in one gram of DNA. Isn’t that cool?

I need to go XKCD  on you for a minute to  explain this data density. The highest capacity USB drive that you can buy today (or at least pre-order) holds one terabyte and weighs about 30 grams. Imagine that you have a DNA based thumb drive that holds about 12 grams of DNA in an 18 gram container. You could put that DNA drive on your keychain, and it wouldn’t be bothered by magnets, and within certain limits the data would persist for thousands of years. Such a drive would store about 8,400 terabytes, and if you it would take 252 kilograms worth of flash memory based thumb drives. That’s equivalent to the weight of Andre the Giant at his peak fighting weight holding this rock:


How much data is that? The Blu-Ray FAQ says a 50 gb dual-layer DVD can hold “over nine hours” of HD video. Since there are 1,024 gigabytes in a terabyte and we’re storing 8,400 terabytes, that’s 1,548,289 hours of full HD video! You could watch cute cat videos for the next 176 years without pausing or seeing the same thing twice.

A Full Soccer Chair

A Full Soccer Chair

Here’s what I’ve been keeping busy with lately!

One of the BORP players was able to get a new Quickie P200 (new to him- they haven’t been manufactured in at least five years), and he asked me to give it “the works”. I took this as an opportunity to try out a few ideas, and this is the result.

First I swapped out the control electronics for something more modern than the 1990-era motor controller, then I got to work on the welding. I posted last month about a new idea for a soccer guard that would be more robust than my stronger design, but also easier to make and cheaper. Call it Version Two- the guy who’s using it seems to like it, but I was finishing the build I realized that the design had space to evolve past some earlier limits of Version One.

Version One was my first venture into designing a welded steel structure that would receive a lot of abuse. I didn’t know how to weld yet, and I didn’t have a good feel for how tough chromoly can be. I knew that we wanted a guard with square corners for better spin kicks, and I knew that I wanted to minimize the weight and rotational inertia of the guard. I spent a lot of time doing calculations and what I eventually came up with had just over a pound of steel in the front four bars- some of the wall thicknesses are 0.035 inches! I’ll admit that I was worried that the guard might cave in from a bad hit, and so I was thinking about what I’d do if that happened.

At the time I designed V1, Kendra was using a Power Soccer Shop guard. My plan in case of damage was to be able to quickly change back to that guard. It wasn’t as good, but it was better than nothing and a lot of people had them. One very important thing for somebody playing for Team USA equipment reliability. We spent two years and many thousands of dollars training and getting to the World Cup- redundancy and contingency plans were important, and I liked the option of borrowing a guard or just bringing the old guard as backup. In the end we brought two complete chairs to the World Cup (but that’s a story for another day…)

Due to my limitations in fabrication abilities at the time, the original mounts sat directly on the P200 frame. The Power Soccer Shop guard just sat at an angle, but the convex front made this less apparent. With the flat front on the new guard I had to include the frame’s seven degree angle  to keep the front face vertical with the existing mounts. It was convenient because all I really needed was a saw and a drill, but now that I have some experience welding I saw a better way, and I saw that including a (stupid) seven degree angle in V2 was completely unnecessary. The player I built V2 for had similar mounts so the bends were required… but welds take a lot of prep work, welds are where things tend to break, and this bend is one of the most highly stressed parts of the guard. In both V1 and V2 I included extra reinforcement (more welding). Starting with a clean slate I realized that I could use a heavier top tube in V3 and skip the whole mess.

An extra benefit of all of this is that by using a round tube I was able to find a source for telescoping sizes of tube to let the guard slide into place securely. In place of four inconvenient screws to secure the guard, V3 just has a quick release pin.

You can see that I also used the guard mount to hold a side guard in place. That was an easy way to go, and I think it’s going to be sufficient to keep the ball from getting trapped. The worst part of this was trying to get the spacing between the two mounts at a close match to the guard tubes. I’ll be thinking about how to make that easier.

The player who owns this chair also wanted a rear guard. This is an allowed attachment that protects the battery box and anti-tip wheels, but also provides a strong and predictable surface for blocking and striking the ball. I’ve never built one before, so I’ll be watching closely to see how this one works out.

Each of the P200’s that I rebuild for soccer gets re-adjusted so that the driver’s center of gravity is placed right over the drive wheels. This improves traction and helps a lot for pivoting to hit the ball… the drawback is that it becomes far to easy to pop wheelies. This wastes time, makes control much more difficult, and can be really unsafe if the chair starts to run up and over the ball. All of the chairs that I’ve reconfigured to be so balanced so far have received additional anti-wheelie casters in the back. This keeps the front of the chair down, and greatly improves handling for the players.

Unfortunately, the same way that the V1 guard mounts were a product of what I was able to do with hand tools in an apartment’s kitchen, the anti-wheelie casters have been attached to the chairs in a primitive way. I use a piece of steel L-stock bolted to the back with two screws, and it takes some good hands to get the wheel on and off quickly. Most of the volunteers at practice struggle with it at first, and I’m probably only good at it because I used to do it three or four days per week when Kendra was training.

I’ve tried a couple of iterations of new attachments before, but nothing I’ve been happy with. I think that putting the wheel into the rear guard is as close as I’ve come to making it easy and strong. Here’s a detail view of how the wheel is attached:

When somebody’s sitting in the chair that wheel is almost an inch off the ground, though it’s almost touching the ground in this picture. The caster is screwed into the end of a tube that sits inside one of those telescoping sections, and there’s a screw that threads into the outer piece and pinches the inner piece. So far I’ve been able to drive the chair around over curb cuts and real-world terrain without getting stuck on anything that wasn’t an obvious problem. The next time I do this I’ll be looking for a way to have the retracted position a bit higher to be more sure that can’t happen.

That’s my latest! I’m really happy that I have a TechShop membership that allows me to have access to the right tools for the job so that I can do all of this stuff. I hope you’ve enjoyed reading about it.


Totally should… hire me!

I’ve had an amazing time traveling the country, working on personal projects, and making new friends for the last few months. However, it’s time for a new chapter. My dream is to work in a product design firm, or at least the R&D department of a company that regularly makes new products. I have assembled my resume and portfolio, and have begun submitting applications.

If anybody out there reading this might now know a position, please email me and let me know. I am focusing on jobs within commuting distance of downtown Oakland, California, but for the right job I am ready and willing to relocate.

Also, if you looked at my resume and portfolio and you have any feedback or criticism, hit me! I’m all ears.