Backsliding… “Jim” painting 80 x 44 inches (image area) — a colorful MESS

Yesterday (February 13, 2007) I completed a first LARGE painting using an airbrush mounted on my CNC machine to paint 22,000 0.4 inch squares (200 x 110 squares) in four transparent colors on Rives BFK paper. One of 17 simple shapes designed to produce tone in even steps from lightest to darkest was painted in each color over each square in order to produce the image.

I programmed a set of the ‘gestures’ (diamonds, and squares in various sizes and an ‘X’ and a ‘+’) to be painted in order to produce the 17 tones in the painting.

"Jim" painting 80 x 44 inches (image area)

Excel spreadsheet I created to calculate value densities using 9 gestures (in rows) combined to produce 16 'tiles' (illustrated at bottom of each column) in roughly equal steps from darkest to lightest values.

screen shot of the program I wrote to apply gesture subroutines to bitmap values to produce program for CNC machine -- the program is built to move to a corner of the tile, then call a subroutine for the value which in turn calls the solenoid on/off and movement commands for one or more of the nine gestures defined to build the tile at that location. Worked very well!

detail -- forehead and hair

detail -- dark side eye

detail -- dark side face

detail -- dark side body

It’s taken the better part of a month to complete and I’ve likely now made most of the possible mistakes which show up quite painfully all over the surface. Gigantic blobs of watercolor leaking from my pigment bottle dripped onto the paper and were then blown all over the place by the air brush as it passed over the painting. Watercolor slowly clogging up the airbrush and leaving vertical ‘light’ areas in stripes. Watercolor spraying out too densely and leaving vertical ‘dark’ areas in stripes. Lines too thick. Lines too thin. Color too rich. Color too lean. The yellow layer offset a column to the left (the other colors were painted after a programming change which calculated the placement differently). Airbrush too close to the paper and too much paint volume resulted in LOTS of color blown out in tiny little splats. Dirty airbrush left broad haloes of color adjacent to lines. Lines unclear and fuzzy-looking.

Here are some details (click for enlargements) of interesting areas of the painting:

movie of painting underway

— Mike

PS… My friend, Jerry, just had a look at this page and phoned to say, “I should just keep my mouth shut… But… You’re totally back-sliding”. After advising me to immediately forward the image to the CIA for their use as ‘proof’ of WMD in Iran (referencing somewhat similar aerial views of Iraq offered up by the White House some years ago), he directed me to Vasarely images familiar from my childhood before (and I’m condensing here) and suggested that I get on to ‘making Art’… Yup… That pretty well sums it up, I think… OK — I’m getting on with it now…

PPS… I’ve consolidated an earlier post below:
My new 17-value airbrush characters seem to be working – now if I can only get my airbrush to not clog up after an hour or 30 minutes or 90 minutes – otherwise it’s gonna require constant supervision which ain’t worth it (and BORING)!

Here’s an image of my spreadsheet calculations of area – I’ve made a set of ‘gestures’ – diamonds, and squares in various sizes and an ‘X’ and a ‘+’:

The ‘X-area’ column is the list of gestures D for Diamond, S for Square, X for diagonals, and P for Plus and the 3-digit number is the area in thousandths that an eighth inch line produces in a 1 inch box.

These are designed to be overpainted in each of red, yellow, blue, and black according to the color and value content of the corresponding area of an image. I’ve got a sample image partially painted in yellow, blue, and red now and it’s pretty much electrically brilliant! There are 17 to the 4th theoretical color possibilities (83,000 plus variations), so PLENTY of variation!

THEN I had to write the program to analyze the image and write the ShopBot code – my code reads an initialization file I wrote in ShopBot code which defines the characters and the subroutines to call them, then the program goes on to analyze each pixel in the image and generate the ShopBot code to position the machine to the pixel and do the painting. The SO,3,1 turns on the airbrush and SO,3,0 turns it off. M2 means Move in 2 dimensions (x,y) – J2 means FAST Jog in 2 dimensions (x,y)

This is actually only the working part of a MUCH longer program – the long program gets input from a screen, checks to make sure it all makes sense, and then calls the appropriate operation, in this case the subroutine above… Here’s what the screen looks like when the program is running (just finished generating the ShopBot code for the color ‘cyan’ for a Jim Winter drawing:

COOL, eh? I added the new code onto my existing program so I wouldn’t have to rewrite all the file and form handling – can’t believe it actually works!!!

I’ve defined some subroutines named after each of the 17 possible values (00 through 16 is white through black) which call the gestures I’ve designed to produce the values — – the first routine listed below is for ‘black’ or value 16 – it calls .313” square, .438 square, .234” plus, and .338” diagonals in turn to produce the ‘shading’ in that area.:

Then I defined the movement for each ‘gesture’ – these are shown below as ShopBot subroutines – you can ‘call’ the subroutine (GOSUB D375 calls the .375 square inch diamond, for example) – the starting corner position is assumed to be in the variable “&xstart” and “&ystart” and the scale factor in &scale. Then the row and column indexes are in &rrr and &ccc variables – in a 100 row x 50 column image, for each rrr (1 through 100) I position to each column ccc (1 through 50) and draw the gestures for that position.

Finally, here’s just the very beginning of the completed code to produce 0.4” squares (&scale = .4) for a very STUPIDLY large drawing 200 squares high by 110 squares wide… Next time I’ll start a bit smaller 🙂

It goes on and on like this – two or three of these commands for each of the 22,000 squares in the drawing – then the next color paints over them, then the next color, and on and on for WEEKS!!!

But it works!!!

— Mike