The landmark exhibition at Harvard’s GSD culls from 75 years of teaching and practice, showing seminal artifacts in plexi covered cases with vertical annotations done in journalistic style. The challenge put to the design team at INVIVIA was to develop an interactive timeline placed at the entrance to the exhibit that would allow visitors to gain a quick temporal context or an in-depth view of a specific period or set of artifacts. The interactive table had to be intuitive to use, show graphic and textual detail in high resolution, support multiple users and be quite robust. Oh, and it had to be finished and installed in 2 months!

We looked at several options. Using a large touch sensitive table was attractive in that it would allow many users and provide a natural interface that would make it easy to browse subjects in depth.  But the cost and complexity of the large interactive surface seemed prohibitive.  A simpler approach, that quickly became the favorite, used top projection onto a matte white surface (plywood covered with adhesive backed matte vinyl) and multi-blob detection to notice where the users hands were. This approach doesn’t allow you to notice whether the user it touching the surface or above the surface, so selecting/deselecting an object becomes difficult.  So we came up with an interaction scheme using different horizontal zones that had different interaction meanings.  The computer vision challenge is to notice only the user’s hands even though there is a continuously changing projected image on top of them.  This gets solved by flooding the table with IR light and filtering out the white light to the webcam with thick Neutral Density filters.

The IR image with multi-Blob detection

White-light view of table with projection

The multi-Blob tracker was a repurposing of Python code used for many touch table applications, based on Markus Gritsch’s VideoCapture python module (http://videocapture.sourceforge.net/). The vision algorithm starts with capturing a base frame and then subtracting each subsequent frame from it to find what moved on the table. In this difference frame we define a Region of Interest and look for candidate blobs.  These candidate blobs are flooded and culled to remove too small blobs generated by noise in the camera signal. Each real blob is measured and these measures are written to a file. Then this process is repeated for the next frame.

We decided on full HD 1920 by 1080PDLPprojectors because of the high visual quality of theDLPimage, the fact that there are many competing projectors in this market segment which keeps the price down, and the relatively high resolution.

We built a crude but effective prototyping area in INVIVIA’s recently renovated top floor space by supporting a 16ft, 2by12” board between the top of the AC control room and a 10ft ladder mounted on tables. This allowed us to quickly build projector housings out of MDF with a bandsaw and drywall screws and attach them to the board with drywall screws and eventually with sliding supports for fine position adjustments.

These projectors must be operated nearly horizontally or they will overheat so each projector housing had a 45 deg. mirror attached to angle the image toward the table below.

Initially we hoped to use 3 projectors arranged horizontally giving us a 5760 by 1080 total image size, but realized after initial testing this that stretching the 1080pixel image across the 32in dimension of the table would not handle the small type we hoped to annotate the images.   We wound up buying an additional projector, turning each projector 90deg. so that the 1920 pixels stretched across the 32in table and shrunk the table length to 4320 pixels for a ratio of 2.25:1.

Projector sled with mirror

Installation view of projector/computer tray and table

The final aspect of the projection setup that needed to be worked out was the IR emitters.  We chose rectangular array emitters normally used outdoors to illuminate parking areas for nighttime surveillance.

The final installation used a well reinforced plywood projector/computer tray hung below a false ceiling.  Openings were cut for the projector light, the IR emitters, and a webcam. Each projector was mounted on a slide that held the 45deg mirror and allowed easy adjustment of the critical space between projectors that almost gave a sense of one continuous image.

Phase3.5: The Maple Circular Stair Tread Routing Machine

INVIVIA’s new spiral staircase was a great excuse to finally get the plotter in shape to do what all self-respecting plotters know how to do well, which is cut useful shapes out of wood; in this case maple stair tread, 1 by 12” hardwood. The plotter’s missing pieces were a high speed router (or wood trimmer) and the aluminum mount to hold the router to the Z axis. I recycled a piece of .3” aluminum stock with a few holes already drilled in it for the Z mount, drilled the 3 holes needed for the Z axis mounting screws and cut a couple of pieces of 2” ‘L’ angle to attach to hold the router. I only had to move the mounting holes once, 8-}, when I discovered that the router needed to be as low as possible to clear the bottom of the Z axis lead screw pillow block. A flexible exhaust hose, bungied to the front of the router connects to a vacuum cleaner that catches the sawdust fine enough to float and gum up the lead screws. Early tests didn’t take long to discover that the trick to getting a clean cut is to use a really sharp up-spiral router bit, Bosch micrograin in this case. Otherwise you will get burn marks and jitter.

Here’s a video of the plotter in action.

12/10/09 Update Phase3: The Carving Machine

Several years ago I had a chance to borrow an amazing device; the Polhemus Scorpion laser scanner that captures the 3D position of a scanning laser beam and orients the beam relative to the the scanner using a magnetic tracking device built into the scanner. Allen was a patient subject and I captured this scan of him. Notice that hair such as eyebrows, mustache and beard and shadows don’t fill in, leaving a hole in the cloud of points that will have to be dealt with later. This cloud can be converted into a mesh model using Polhemus’ FastSCAN software as you see here. Since I wanted to cut this surface using the plotter I needed to convert the mesh into a set of machine instructions. For this I used the very excellent MeshCAM application which analyzed the model and produced a set of toolpaths for the several different cutters needed to shape the insulating foam I used. For the cutter I re-purposed a UNIMAT-SL mini lathe/mill that my father game me long ago by machining a mount to hold it firmly on the Z axis and another mount to reverse the motor away from its original position parallel to the cutting head. I chose this mini mill instead of the standard router because it had a keyed chuck and collet that would allow me to use a wide range of cutters. Routers tend to limit the cutters to router bits of a certain type. The final model turned out to be 8″ x 13.5″ x 5.6″ so I decided to use 1″ insulating foam because the foam cell size is quite small and uniform, the material is cheap and cuts nicely. The downside to the choice is that I had to glue 6 – 8″ x 13.5″ pieces together and my choice of superglue, then when that failed Titebond, caused me lots of grief.

I’m hoping that the foam glue I tested will work out for the next carving. Notice that I needed two laptops for this project: one to control the plotter and do the cutting, the other to capture sound and a frame every second from a webcam to record the process.

The cutting sequence starts with roughing where much of the unwanted material is removed. One imagines the roughing process was invented by a frustrated cubist from the look of the result of the roughing process composed by MeshCAM. The next steps begin to reveal the form of the object to be uncovered (discovered?) within the raw material.

Each pass uses a finer cutter, cutting a little deeper and revealing more of the detail of the original model.Problems with control of each axis were revealed at different points in the 7 step process. Solving these meant discovering faulty electrical connections, bad bearing alignments, etc… Tuning the Z axis so that it doesn’t lose steps either going up or down has been a challenge.

Next Steps Before changing direction again I feel I should refine the carving process so that I can carve a form with the minimum of technical interruptions from the plotter. I would welcome input from the INVIVIA community, but my guess is that next should be a rapid-prototyper attachment for the Z axis that uses ABS or other heat formable plastic. That feels like the right additive complement to the subtractive carving approach shown here…

Edith’s presentation included an informative briefing on the following topics:

• Digital Natives: Who are they and what’s to be learned?
• 21st Century Skills: What’s being proposed?
• Lessons for Designers and Decision-makers
• A peek into the future: INVIVIA XUI Video presented by INVIVIA Co-Founder, Peter Mabardi

The event was hosted by:

• Sean Belka Director of FCAT
• Amanda Chu VP of FCAT
• Melinda Kuleszka Manager of FCAT of Digital Consumer Practice
• Carl Yang Director of Digital Consumer Practice
• Zack Ventress Director of Digital Consumer Practice
• Danielle Duplin EPD of FCAT

Edith Ackermann and Peter Mabardi at Fidelity

Edith Ackermann at Fidelity

Today was the first set of studio reviews for Science Fiction @ NuVu. The two studios being reviewed were Fusion Energy and Nano Technology. In both courses the students learned about the physical sciences. At the same time, they designed future products and systems in an attempt to apply their newfound scientific knowledge. The courses are very hands-on self-directed.

Nuclear Fusion

I was only able to attend the last two presentations for Nuclear Fusion. A group of two young women researched nuclear fusion power and the Manhattan transportation system. The other group of four guys (Astranavis) researched a fusion-driven spaceship for reaching Gliese 581 G. Both groups gave a very good effort to design complex systems in a two week studio. The Manhattan fusion group invested most of their resources in budgeting the power from the fusion plants. While Astranavis focused their efforts on innovating forms and processes for designing an optimal spacecraft of the future. The Astranavis also had a well-executed consolidated digital presentation and a non-digital presentation as a backup.

Nanotechnology

The nano-technology studio was situated on the broad reaching physical principles of molecular science. The challenge was for the students to be able to take these principles and run in a science-fiction fantasy direction. Many of the projects were focused around the literal or metaphor of a seed. The students took a microscale physicality and built full scale objects out of them. The most abstract of these projects was a presentation on intention as a seed in the pulp of neurons. It was an investigation of how ideas and the intention to commit to an idea is grown in the connections between neurons. So meta!

My personal favorite of the nano tech projects had the poorest presentation. The concept was to take a water bottle and transform it into a truck. The concept was magical. Break down water bottles into self-reproducing modular substructures in the shape of trucks with the hope that at some scale the composition of this arrangement of mini trucks would form an actual truck. Unfortunately during the presentation the student froze and was unable to explain the origins or parallels to his ideas.

Overall, it was great work from smart youth guided by genius professors.

Catch the Bus is a cross-platform real-time MBTA Bus app. It is currently available for iOS and Android. PocketMBTA is the competitor to Catch the Bus. PocketMBTA is only available for iOS. Both applications recently released significant updates. However, Where Catch the Bus is much easier to navigate, PocketMBTA has better mapping features. Below is a quick exploration to merge the functionality of the two apps for Android. Please note that these sketches are not graphically rendered.

The second event is September 17th at The Studio Museum in Harlem.

Getting the plotter to work at all was Phase1, now that I’ve got a better idea of the the range of images one can make when you can move drawing implements accurately in 3-space we’ve entered Phase2 of the the CNC Plotter project.

This crude sketch for the print I hope to execute sets the context for the experiments.  It combines both raster and vector elements in a way that should both demonstrate the flexibility of the machine and the approach and be a compelling print in its own right.  To date I have only realized the raster portion of the print as you will see demonstrated below.

I began by experimenting with as many different drawing implements as I could get my hands on, starting with ball point pens, pencils, markers, crayons, drafting pens…many of them left over from the days (35 years ago) when I was a printmaker. If you want a nice fine line a drafting pen or ball point pen works very well, but after a while that tiny line is not as expressive as needed and gets pretty boring…

Big thick graphite pencils have the most continuous tonal range but have one fatal flaw that I couldn’t figure out how to get around:  they have a certain amount of memory.  When you push very hard to make a rich black mark, they get roughed up and remember it, and show it by making the subsequent marks in the line darker than they need to be.

Conte Crayons, and their cousins the charcoal crayons, seemed to be the best substitute and have a certain random quality to the mark that actually makes them superior in many ways.  You have to hold the crayon in a holder that can be mounted on the Z axis of the plotter.  I do this by drilling a hole in the tip and hot-melt-gluing a small piece of the square Conte crayon in then machining it down to a diameter that is just slightly wider than the raster that I’ll be using for that image.

Conte and charcoal crayons have their good qualities but limitations as well.   Conte is very soft, makes a nice black mark but wears down so quickly, because it is so soft, that it if you make a tip long enough to last through a whole print it will break off.   Charcoal is much harder, will last much longer, but doesn’t make really dark marks, shown in the left image, below.  To get a full toned print, I decided to use a two-pass or duo-tone printing sequence.  I start with an image of just the shadows (middle image) and finish by printing with the harder charcoal over it.  Together they produce a rich, full toned image.

Part2 (next steps)

In order to finish the print I need to build some way of :

• twisting, scraping at an angle, larger pieces of charcoal
• holding a brush, probably at an angle, dipping it in paint
• holding an airbrush,
• etc…

This means I need to add another motor and controller to the system and hope that my laptop and Mach3 CAM software will let me control it.   We’ll see…

cheers, ronmac

• organic imaging using DIY Bio technologies
• DIY rapid prototyping, experimenting with application approaches, binders and curing techniques
• sculpture/image experiments using a router cutting and ink-jet head to both form and image onto 3D surfaces.

In addition one can imagine acquiring a high powered IR laser and beginning to cut plastic and wood for 2.5D rapid prototyping, or attaching a plasma cutter and cutting through sheets of metal with speed and high precision to make architectural elements…etc.

Over the past several months I’ve been assembling the pieces needed to, finally, start building the prototype.  Here we see the beast with the major structural elements in place and with the X axis functioning, though not driven by a lead screw yet.

“Hello INVIVIA” Update (8/17/09)

Having installed the ball screws for the X and Y axes and the little lead screw for the Z axis, as a test that the three axes were working I made  a Hello World example, or in this case Hello INVIVIA..   To do this I had to make a little Sharpie pen holder out of four pieces of acrylic and mount these to the simplest connection to the Z axis slide.   If we really want to use the device as a pen plotter it will take a bit more work to devise a way to change pens under computer control and build and interpreter/controller so that it understands the HP Graphical Language which is what pen plotter speak.

Here’s a little video of the ‘Hello INVIVIA’ performance…

In order to really begin “using”  the plotter I will need to cover the ball screws to keep dust and other gunk out or they will stop working quickly.  In addition, as you probably notice, there is no ‘work surface’, just a cardboard box with a piece of plywood on top as the drawing surface.  I did this so that the working parts would be exposed for the video, but one of the next tasks is to cover the bottom ball screw with a slotted, layered sheet of MDF (medium density fiberboard) after the bottom ball screw has its protective sheath.  Then the next part I will build will be an adapter to hold a small router on the Z axis so that I can begin to carve stuff…

Motor Testing Prints

Each axis uses a stepping motor driven by a very simple, cheap kit controller card, powered by a scrounged together power supply.  The X and Y axis steppers go through a 4:1 gear(pulley) box to help them drive the considerable weight of the axis elements while the Z axis works well direct drive.   Steppers are virtual magnetic  springs with very high holding torque (in this case 450 oz-ins) but get progressively weaker the faster they go.  So the motor top speed needs to be fine tuned so that you get the fastest action possible without stalling out.   The following test prints show the motors stalling out at different points in the print process.  They resemble an exercise you might give a beginning typography class.

cheers, ronmac

Working with the 3D Motion Capture System at the Media laboratory of the Institute of Architecture and Media at Graz University. Narrative strategies are developed out of movements in space and implemented in different media – as films and as printed or built objects.