There's a picture going around now of a dress. And there's a surprisingly firm split in how people perceive it. Some say the dress is "obviously" white and gold, others say it is "obviously" blue and black.
I think, like the airplane-on-a-treadmill one, the problem lies not with esoterics of color perception, but in definitions. Do you mean the colors that are in the picture, or the color the real object is likely to be?
The latter is, of course, not possible of derivation from the image supplied. It is obviously taken in strong backlight, the lighting and tones are strongly suggestive of outdoors in sunlight on a clear day, and the trim appears at the least of a satin finish, possibly even shinier.
But you don't know the response curve of the CCD or what adjustments the image has been through. So, based on what evidence is available, the conservative hypothesis is white or off-white with a trim that is somewhere between gold, metallic copper, down to a light coppery-brown with a slight sheen to it.
But that doesn't mean that "is" the color of the dress. Like so many things, it depends on image steps and local effects (the gamma and color balance of the computer screen you are viewing on, the lighting environment you are sitting in while viewing it, etc.) Given these, a wide range of individual colors is possible. Up to and including black trim if you define "black" as a satin finish with a surprising amount of yellow sneaking in.
It's like the problem of the color of the Martian sky. To what color perception? Your eyes naturally gray-card in every environment they are in (up to a certain range; they can't compensate all the way down to candle light, and strongly saturated color environments -- like viewing the world through rose-colored glasses -- will retain a tint even after an hour of adjustment.) If you were transported instantly to Mars, you might see the sky as one color. If you were standing out there all day, adjusted to the sunlight there, you'd see another.
And it is absurd that people who work every day on computers, people who often are involved in art and image as part of their jobs, don't even see the need to point this out when discussing the dress.
This underlies one again this lacunae that much of my profession hits over and over again. When I do lighting or sound I have no choice but to grapple with what is actually there. And to do my best to shape the audience perception in the directions I want.
The vast majority of the people I work for and around can only work on the level of what they perceive, and conversation stops dead on that bottleneck. Because I am well aware it looks dark or sounds soft, and I am taking steps to ameliorate this, but those steps have little or nothing to do with turning up the lights or the microphone feeds.
Friday, February 27, 2015
Wednesday, February 25, 2015
Knot Working
I still need another job.
The props stuff is keeping me busy, but with only a sound op gig, a small lighting design, and some microphone rentals I'm just barely going to scrape by.
I was messing around with knotwork today -- or more specifically, looking at a lot of stuff about Islamic interlace patterns. The idea was to work up something for my new Jedi Holocron project that takes the "Millennium Falcon Circuitry" pattern of the last one and moves it to more of a repeating decorative pattern...and the religious-art connotations don't hurt, as this is a design for a Jedi Temple.
Not sure why I thought of going in that direction. Maybe memories of the fantastic clockwork facade of the Institut du Monde Arabe in Paris.
The props stuff is keeping me busy, but with only a sound op gig, a small lighting design, and some microphone rentals I'm just barely going to scrape by.
I was messing around with knotwork today -- or more specifically, looking at a lot of stuff about Islamic interlace patterns. The idea was to work up something for my new Jedi Holocron project that takes the "Millennium Falcon Circuitry" pattern of the last one and moves it to more of a repeating decorative pattern...and the religious-art connotations don't hurt, as this is a design for a Jedi Temple.
Not sure why I thought of going in that direction. Maybe memories of the fantastic clockwork facade of the Institut du Monde Arabe in Paris.
So I'm slowly getting used to both Inkscape, and GIMP. Flipping back and forth between them is still...interesting...however, as the key commands are completely different for each. In fact, because Inkscape is running on Xquartz via a Java VM, it remaps command (Mac standard) to control. So something as simple as saving the file takes an extra little bit of concentration.
I still have no idea how to proceed on my power issues with the DuckLight. Seems like I need to live with the idea of larger battery packs if I want the full output power, and add on-board regulators. Which not only adds parts, and footprint, but also means you'd have to change jumpers or something for all those applications where a smaller battery pack is more appropriate.
Hrm. Maybe regulating the ATtiny down to 3.3 volts regardless of battery source makes the most sense. 2xAAA just doesn't light anything but a red LED anyhow, and that's the only set that would be too low for even an LDO. And with a powerful enough regulator, it could supply an XBee, meaning I wouldn't really need a custom daughterboard for those.
One thing I have figured out is what I want to do with those flexible USB lights I picked up for a buck each at Wallgreens. Make little Steampunk-Tiffany task lights out of them. Add a laser-cut acrylic clip/magnet on one end, paint the flexible rod up a nice brass, stick a super blue LED in, and pull some painted/dyed PETG over a hand-carved buck to make a shade.
Now if only I had some sketches I liked for the Raygun. I need to start getting client approval and move into the next design phase!
Monday, February 23, 2015
Jaffa, Cree!
Oh, did I make that joke already?
Internet is back, BTW. It took eight phone calls, an hour of navigating phone "help" menus, three service calls, and over a week...but they finally figured out the modem was dead. You'd think they could ping it and find out, but apparently that particularly modem typically fails in a way that looks like a bad line from both ends. Funny thing is, not even the service techs...two of them, lugging bags of electronic gear from their van...had tools to see if the line actually connected. Only a DSL modem will actually tell you anything, and because of the secure installation procedure it is non-trivial to swap in a test unit.
Only good side to the affair is it gave me the excuse to yank my old desktop and monitor and all the associated cruft and clean up under my work table. It looks much neater and cleaner now, and I can use my scanner without getting a back injury.
Discovered a puzzling problem with the DuckLight board. I noticed it was much brighter running off the 5v regulated supply of a USB port than it was off the 3xAAA battery pack. I thought this might be an amperage issue but a little more experimentation shows it to be voltage related.
Which is odd. The forward voltage of green LEDs is under 4 volts (3.7 seems typical). The voltage drop of the AMC7135 chip is a mere 0.12 volts. A 3x battery pack should thus be quite sufficient.
Oh, but wait. Calculating with the smaller voltage of nickel-metal hydride (the Sanyo Eneloop rechargeables I use almost exclusively) brings the 3x battery pack to a mere 3.6 volts. Which is far enough into the curve to experience a significant loss of luminosity.
And I had already discovered that on 2xAAA (my designed footprint for the first board) only the red LED lit properly; the green was obviously not getting sufficient voltage.
Well, shucks. The rated output on lithium polymer packs is 3.3 to 3.7 volts -- meaning once again that the most common green LED chemistry won't light at full power. Especially not if I try to run a 3.3 volt bus (to allow direct connection of certain sensors and XBee radios).
So what are the options? Switching to alkaline is not actually a help. Alkalines drop very rapidly in voltage from full charge. In addition, their nominal rating is given in no-load -- unlike NiMH's, which give the nominal voltage rating under design load (due basically to lower internal resistance).
Going significantly over and regulating down to 5 volts would make sense for a more complex project. At a draw of 1 watt or more, though, that's a hefty regulator -- and a lot of heat from wasted wattage. A dual NiMH pack, for instance, regulated to 5 volts, would have to burn off over five WATTS. That's at the peak of what a TO-220 package can handle with a bolt-on external heat sink.
Splitting the difference, a 4x battery pack delivers 4.8 volts nominal -- that's pushing up to 1/4 of the wattage into the regulator, which has to burn it off -- and at full charge can get pretty close to 6 volts. Which fortunately is while out of spec still within the range of what the ATtiny can tolerate! It is also twice the footprint of the board in flat pack and basically annoys me as a form factor even in quad.
(And in case you are wondering, all those Cree flashlights get away with it because "white" LEDs have a lower voltage drop than the common green ones.)
And, bah -- four fully charged eneloops are sufficiently above the voltage spec that the ATtiny shuts down. Which means I would need to include an LDO in order to operate the green LED at full efficiency. Or....regulate just the ATtiny, perhaps at 3.3V for sensor and XBee compatibility...well, according to the literature the AMC7135 really likes to be between 4.5v and 6v. Gets way too hot above that. Like most LDOs, the highest efficiency is when the voltage in is very close to the voltage out.
Well, I still have to finish porting my "blink" code to the new board, and see if there is even possibly enough space left over in program memory to do any of the other tricks I want. One issue from the old Piranha board that the Cree makes a lot more of a problem is the stair-stepping at the low end of the intensity scale. With only 255 steps in my pulse generator, the difference between 1/255 and 2/255 is a little too obvious in LED intensity. So I'm reading up on dithering techniques. (I can't simply increase the PWM bit depth, as I'm running at 8 MHz on internal oscillator and the PWM frequency is already close to critically low).
I also need to do a bake test to make sure the system can handle being ran wide open for a significant interval. I've already noted that 3W is at the low end of theatrical viability. Fortunately, a lot of applications can be served without full RBG -- instead hanging a 3W or even 10W single-color LED on the board and running the current regulators in parallel mode.
Another change that's on the horizon. The old RGBs are slipping in the Chinese suppliers to make room for new cheaper RGBW's. So far no affordable RGBA, but I have my eye on a few affordable RGB-Warm White already. Which is why my board is a four-channel. And why the ATtiny84 -- to give enough extra I/O pins for external sensors/controls. Although I still may end up just going into an ATmega eventually. Especially if I chose one with native USB support. Those are nasty little surface-mount jobbies...but at least they aren't BGA!
I'm also seriously contemplating revamping my headers completely and making the duckNode Trinket compatible. There's a LiPo backpack in that format, for instance. And in the obverse, I could make my XBee shield cross-compatible. The downside is I want to achieve everything possible from the ICSP header alone -- plus a stand-off, which the current iteration omits -- so there is no need to solder header pins to the board in order to program it or even to integrate it with radio link or power regulation. Having pins soldered on is one more thing to work around or to have to remove when cramming the final board into a prop, and the whole purpose of this exercise is to produce the most minimal footprint, lowest parts count and cost to bring full PWM control of 4W RGB/RGBW LEDs.
(So many TLAs there, I'm starting to feel like I work at NASA!)
Internet is back, BTW. It took eight phone calls, an hour of navigating phone "help" menus, three service calls, and over a week...but they finally figured out the modem was dead. You'd think they could ping it and find out, but apparently that particularly modem typically fails in a way that looks like a bad line from both ends. Funny thing is, not even the service techs...two of them, lugging bags of electronic gear from their van...had tools to see if the line actually connected. Only a DSL modem will actually tell you anything, and because of the secure installation procedure it is non-trivial to swap in a test unit.
Only good side to the affair is it gave me the excuse to yank my old desktop and monitor and all the associated cruft and clean up under my work table. It looks much neater and cleaner now, and I can use my scanner without getting a back injury.
Discovered a puzzling problem with the DuckLight board. I noticed it was much brighter running off the 5v regulated supply of a USB port than it was off the 3xAAA battery pack. I thought this might be an amperage issue but a little more experimentation shows it to be voltage related.
Which is odd. The forward voltage of green LEDs is under 4 volts (3.7 seems typical). The voltage drop of the AMC7135 chip is a mere 0.12 volts. A 3x battery pack should thus be quite sufficient.Oh, but wait. Calculating with the smaller voltage of nickel-metal hydride (the Sanyo Eneloop rechargeables I use almost exclusively) brings the 3x battery pack to a mere 3.6 volts. Which is far enough into the curve to experience a significant loss of luminosity.
And I had already discovered that on 2xAAA (my designed footprint for the first board) only the red LED lit properly; the green was obviously not getting sufficient voltage.
Well, shucks. The rated output on lithium polymer packs is 3.3 to 3.7 volts -- meaning once again that the most common green LED chemistry won't light at full power. Especially not if I try to run a 3.3 volt bus (to allow direct connection of certain sensors and XBee radios).
So what are the options? Switching to alkaline is not actually a help. Alkalines drop very rapidly in voltage from full charge. In addition, their nominal rating is given in no-load -- unlike NiMH's, which give the nominal voltage rating under design load (due basically to lower internal resistance).
Going significantly over and regulating down to 5 volts would make sense for a more complex project. At a draw of 1 watt or more, though, that's a hefty regulator -- and a lot of heat from wasted wattage. A dual NiMH pack, for instance, regulated to 5 volts, would have to burn off over five WATTS. That's at the peak of what a TO-220 package can handle with a bolt-on external heat sink.
Splitting the difference, a 4x battery pack delivers 4.8 volts nominal -- that's pushing up to 1/4 of the wattage into the regulator, which has to burn it off -- and at full charge can get pretty close to 6 volts. Which fortunately is while out of spec still within the range of what the ATtiny can tolerate! It is also twice the footprint of the board in flat pack and basically annoys me as a form factor even in quad.
(And in case you are wondering, all those Cree flashlights get away with it because "white" LEDs have a lower voltage drop than the common green ones.)
And, bah -- four fully charged eneloops are sufficiently above the voltage spec that the ATtiny shuts down. Which means I would need to include an LDO in order to operate the green LED at full efficiency. Or....regulate just the ATtiny, perhaps at 3.3V for sensor and XBee compatibility...well, according to the literature the AMC7135 really likes to be between 4.5v and 6v. Gets way too hot above that. Like most LDOs, the highest efficiency is when the voltage in is very close to the voltage out.
Well, I still have to finish porting my "blink" code to the new board, and see if there is even possibly enough space left over in program memory to do any of the other tricks I want. One issue from the old Piranha board that the Cree makes a lot more of a problem is the stair-stepping at the low end of the intensity scale. With only 255 steps in my pulse generator, the difference between 1/255 and 2/255 is a little too obvious in LED intensity. So I'm reading up on dithering techniques. (I can't simply increase the PWM bit depth, as I'm running at 8 MHz on internal oscillator and the PWM frequency is already close to critically low).
I also need to do a bake test to make sure the system can handle being ran wide open for a significant interval. I've already noted that 3W is at the low end of theatrical viability. Fortunately, a lot of applications can be served without full RBG -- instead hanging a 3W or even 10W single-color LED on the board and running the current regulators in parallel mode.
Another change that's on the horizon. The old RGBs are slipping in the Chinese suppliers to make room for new cheaper RGBW's. So far no affordable RGBA, but I have my eye on a few affordable RGB-Warm White already. Which is why my board is a four-channel. And why the ATtiny84 -- to give enough extra I/O pins for external sensors/controls. Although I still may end up just going into an ATmega eventually. Especially if I chose one with native USB support. Those are nasty little surface-mount jobbies...but at least they aren't BGA!
I'm also seriously contemplating revamping my headers completely and making the duckNode Trinket compatible. There's a LiPo backpack in that format, for instance. And in the obverse, I could make my XBee shield cross-compatible. The downside is I want to achieve everything possible from the ICSP header alone -- plus a stand-off, which the current iteration omits -- so there is no need to solder header pins to the board in order to program it or even to integrate it with radio link or power regulation. Having pins soldered on is one more thing to work around or to have to remove when cramming the final board into a prop, and the whole purpose of this exercise is to produce the most minimal footprint, lowest parts count and cost to bring full PWM control of 4W RGB/RGBW LEDs.
(So many TLAs there, I'm starting to feel like I work at NASA!)
Saturday, February 21, 2015
Dead Head
Ran out to the Rose Garden to take some pictures, but the roses are very much not in bloom at the moment. Whoops. We stayed until it got cold and dark anyhow. Yes; a sheet of foam-core works very well at providing a nice diffuse fill light....when there's enough direct light falling on it.
Ran the prototype current-controlled DuckLight for about four hours without any sign of overheating or the LED being overdriven. Next I think is an acid test; put a minimal heatsink on the LED and run it full-out for an hour or two. Those AMC7135's are totally the ticket!
The Holocron enquiry got one response. I'm working up a new Holocron design for a Jedi Academy now. Have in mind a combination I think will work, but haven't actually gotten into Illustrator (rather, InkScape) yet.
HP is now on my "nice" list. The scanner software I was using demanded I upgrade, told me upgrades were no longer free, and threw up its hands when presented with a 64-bit OS and what was apparently a 32-bit scanner driver. "Go call HP and see if they have any drivers," was all the software could offer. So I did, and HP had...a completely free and compatible scanner package I'm using now instead.
And I finally got off one sketch of the "art gun" direction for the raygun commission that I actually like.
Sure, I have to work on the proportions some more, and I have no idea how to machine some of it, but it in my mind finally achieves that blend of looking like the shape came out of art school but the details and machining are tight and quality.
It may not be quite period-looking enough, though. (Especially since to my mind the perfect combination would be stained and varnished wood furniture, and aluminium parts anodized in a pale green.)
So continue the sketches. Eventually I'll stumble upon a few that are decent enough to show to the client.
Ran the prototype current-controlled DuckLight for about four hours without any sign of overheating or the LED being overdriven. Next I think is an acid test; put a minimal heatsink on the LED and run it full-out for an hour or two. Those AMC7135's are totally the ticket!
The Holocron enquiry got one response. I'm working up a new Holocron design for a Jedi Academy now. Have in mind a combination I think will work, but haven't actually gotten into Illustrator (rather, InkScape) yet.
HP is now on my "nice" list. The scanner software I was using demanded I upgrade, told me upgrades were no longer free, and threw up its hands when presented with a 64-bit OS and what was apparently a 32-bit scanner driver. "Go call HP and see if they have any drivers," was all the software could offer. So I did, and HP had...a completely free and compatible scanner package I'm using now instead.
And I finally got off one sketch of the "art gun" direction for the raygun commission that I actually like.Sure, I have to work on the proportions some more, and I have no idea how to machine some of it, but it in my mind finally achieves that blend of looking like the shape came out of art school but the details and machining are tight and quality.
It may not be quite period-looking enough, though. (Especially since to my mind the perfect combination would be stained and varnished wood furniture, and aluminium parts anodized in a pale green.)
So continue the sketches. Eventually I'll stumble upon a few that are decent enough to show to the client.
Nile Project
Started the school tour (9 AM performances!) That show is open now, so another plate is quietly spinning...
Also shipped the next eight M40 grenades. That makes 35 of the things I've sold now. The new
processes didn't work quite as well as I wanted, and I still need to purchase some new tooling, but it got down to under three hours of labor each -- less than two for the machining.
Someone asked for the files on the Holocron and I've gone ahead and indicated I will produce a kit if requested. Perhaps I should start an INT thread at the RPF as well?
That makes the prop priority the Raygun. Although the final ship deadline is a ways off, it would be better business if I got it done a lot sooner -- soon enough for other "space tiki" fanatics to decide they want one, too.
And the AMC7135's I've been waiting on finally showed up. I enquired at a couple local stores for solder paste and checked prices at some online suppliers, but I was able to solder up the first SMD with a regular iron and some nice Kester silver solder I picked up at Al Lasher's Electronics.
There's a few mistakes on the PCB. I expected that. The trimpot sits too close to the ICSP header, and I'd managed to mis-identify the correct external clock pin for programming. Well, that's what jumpers are for.
The main purpose of the board was, after all, to test the AMC7135's. And after I fixed my screw-up with the ICSP wiring, it came through. I had to stop the full-power test because the LED needs a heat-sink if it is to be operated all out, but the AMC7135's appear to be limiting the current quite nicely, AND are responding correctly to the ATtiny. After a couple of hitches I have software PWM running. Seems a wee bit unstable -- so when I make the next version it will have a filter cap across the power lines of the DIP, and perhaps something on the RESET pin as well.
But before I get deep into revamping the PCB, I have software to write.
processes didn't work quite as well as I wanted, and I still need to purchase some new tooling, but it got down to under three hours of labor each -- less than two for the machining.
That makes the prop priority the Raygun. Although the final ship deadline is a ways off, it would be better business if I got it done a lot sooner -- soon enough for other "space tiki" fanatics to decide they want one, too.
There's a few mistakes on the PCB. I expected that. The trimpot sits too close to the ICSP header, and I'd managed to mis-identify the correct external clock pin for programming. Well, that's what jumpers are for.
The main purpose of the board was, after all, to test the AMC7135's. And after I fixed my screw-up with the ICSP wiring, it came through. I had to stop the full-power test because the LED needs a heat-sink if it is to be operated all out, but the AMC7135's appear to be limiting the current quite nicely, AND are responding correctly to the ATtiny. After a couple of hitches I have software PWM running. Seems a wee bit unstable -- so when I make the next version it will have a filter cap across the power lines of the DIP, and perhaps something on the RESET pin as well.
But before I get deep into revamping the PCB, I have software to write.
Monday, February 16, 2015
Patch Pockets
Going into tech, no time or money for laundry. Needed to haul that sewing machine out to make more mic belts anyhow, so did some haphazard repairs on a couple pairs of torn pants. One had rear patch pockets. Which meant there was matching material I could salvage to cover a nasty hole.
Short two primers or my latest grenade order would be done. I hinted I'd make a ninth as a special gift to the customer by asking him to pick a number between M38 and M230. He picked M56, which doesn't help me at all -- is not one of the ones identified in the Aliens universe. Ah, well. Means I can do whichever one seems more interesting -- or least annoying.
Got up early and spent a long day repairing mic elements. Every time I dig into the bag full of broken elements, I find a couple more repairable ones trapped in the lining or under something else. I should be okay for the current show, then.
And the raygun got approved for metal. Metal, but still towards the Barbarella end. Which means is time to drop the whole "plywood cutout" idea and see what I can do if I free myself to imagine any kind of intersection I can machine (or CNC) between aluminium, brass, and acrylics.
Short two primers or my latest grenade order would be done. I hinted I'd make a ninth as a special gift to the customer by asking him to pick a number between M38 and M230. He picked M56, which doesn't help me at all -- is not one of the ones identified in the Aliens universe. Ah, well. Means I can do whichever one seems more interesting -- or least annoying.
Got up early and spent a long day repairing mic elements. Every time I dig into the bag full of broken elements, I find a couple more repairable ones trapped in the lining or under something else. I should be okay for the current show, then.
And the raygun got approved for metal. Metal, but still towards the Barbarella end. Which means is time to drop the whole "plywood cutout" idea and see what I can do if I free myself to imagine any kind of intersection I can machine (or CNC) between aluminium, brass, and acrylics.
Up Periscope
The hamster is sick over at my ISP and my regular internet connection is gone. Paying Xfinity for a short burst of service every day, like a boomer surfacing once a day to pick up new radio instructions.
Was a bit sick myself there and fell behind in finishing the last prop order. Work table is covered right now with M40 grenades getting the final going-over with emery paper and steel wool. Plus wireless microphone elements in need of repair before Tuesday tech rehearsal.
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