#apertus IRC Channel Logs

dmj_nova: if I can allow myself to answer, the direct interface to the sensor varies

FergusL: yeah, first time designing an interface for a sensor if you can't tell

I've been using Arduino for about a year, it was a great first step

I've had a fair bit of experience with other sorts of electronic stuff

FergusL: probably a serial interface would be less of a pain to work with if you have many sensors

yes, definitely, but sensors don't generally have directly serial outputs, most of the time they're connected to a microcontroller which in turn process the signal and sends serial messages

10 "digital" lines per sensor

what is the sensor you're looking it ?

FergusL: I'm building a new kind of linear encoder with absolute positioning via graycode

is it for something apertus-related or ?

oh nice !

and most of them can't do absolute positioning so you've got to recalibrate every time you start it up

yep

hm, some encoders do that

(well, cheap by industrial robot standards, yes)

ha yes...

FPGA programming is *always* expensive anyway

but it's still a big chunk of change for an individual

BTW, I'm trying to design a moco rig for indie film

heck, my stepper controllers are $35 bucks

Well, at the moment the only thing that's been built is an arm

so rotation and translation

what range to you plan to achieve ?

ish

perhaps more on one translation axis

which should be good for having actual ground truth 3D coordinates for each frame (rather than having to spend hours and hours matchmoving in blender)

FergusL: and potentially be able to film the same scene simultaneously in multiple locations

the usual technique is to shoot one or two passes at a location

yep, though for example you could film a location and two actors in separate locations and have the rig respond to both

but the bigger deal is enabling multiple passes and allowing freer use of vfx in smaller productions

often you can get away without much masking by diffing against the background plate, but that only works for tripod shots

FergusL: ToS enabled us to do good tracking at all

I could give you plenty of shots that are untrackable

one tracking shot is fine, and entire scene...takes a lot of work

absolutely yes, that's what is used on bigger setups

not something an indie production could use for half their film

and I think you can't avoid expensive sensors which are a crucial point

well, as long as you stay within the stepping capacity of the motors you don't need hardly any sensors for moving the rig accurately

the sensors are just an input mechanism

morning everyone!

dmj_nova: well, the sensor interface largely depends on what kind of data (amount, interval) you need to transport over what distance and how reliably

yeah, and the sensor is pretty much inherently digital

IIC == I2C?

yes I²C = I2C = IIC

seeing as how the sensor will necessarily be used with mocobus steppers

s/_/)

The Axiom is supposed to eventually have a mocobus interface.

you mean mixed with both sensors and motors?

ah

how so?

termination, voltages, etc, but not the actual protocol

and rs-485 can be used over quite a distance

now TTL levels on the other hand will not be reliable over more than a few meters at most

they also suffer from EMI and offset voltage issues

so, at first glance that looks to me like you are building a high security transport vehicle but you decide to send half of the data via pigeons

could be, I haven't tested mocobus with anything longer than a couple meters

I could ask Chris about the TTL thing though

hooray, I just had a power failure

I suppose I'm rather limited to the constraints of mocobus anyway :/

which would be a huge waste of effort and a giant fuck you to dynamic perception

rs-485 is not limited to 2 endpoints

Bertl: there must've been some good reason for the TTL logic

I might do that when he gets back to me with my last set of questions

so far their engineering has seemed sound to me (though everyone makes mistakes)