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Old 04-26-2009, 10:53 AM   #1
KingDani
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stylus calibration problem

first , i wanted to verify something , wacom stylus is a sort of magnetic field technology right? it that's true , i should first state an interesting obeservation:
when the device is in zZz mode , if you try to wake it via stylus ,the most likely result will be the stylus become disabled. well , i observed that if you put the stylus tip , very close but not attached to the screen , the screen refreshes , and after that you can go on with writing. unlike when you do it in one step and stylus gets disabled , this , at least in my experience works perfectly , done 20 pages with no locks.
i think this has something to do with magnetic fields of screen , but i also suspect they developpers of firmware wrote a way for this in their code. any suggestions?

second , my DR has a strange behaviour , the right half of the screen is more accurate than the left , i can write whatever i want on the right part , with no glitches or deviated screw ups , but at left , i get 5-7 milimeter written material from where i originally intended. any similar experience?

PS : i have done a complete walkthrough with pictures and several pics of DR1000s exclusively for our Persian Handheld community , but i thought i could publish it here too , anyone interested? you think it could new arrivals ?
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Old 04-26-2009, 03:09 PM   #2
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I think each screen is different. I have found that I can get reasonable calibration by deliberately missing the mark during the calibration process, by a few millimeters. A bit of trial and error is required, of course.

As to waking from sleep mode just by the pen almost touching the screen, I have noticed the same thing. I don't know what the underlying technology is. But I have found that if the stylus gets disabled, I can navigate to the setup, turn off the stylus, exit setup, re-enter it, and turn the stylus on, and it will work again with no need for a restart. Still annoying, but less so.
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Old 04-26-2009, 04:51 PM   #3
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Well I've tried all sorts to get a decent calibration. It is just hopeless. I too find it worse on the left than the right. I'm just hoping that the next firmware will improve on it. My replacement DR is better than the original but it is still useless towards the edges.
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Old 04-26-2009, 05:29 PM   #4
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phtwaite , you mean the replacement actually has better calibration results than the old one? well that's horrible news for me , not being able to request for a replacement ( i live in Iran and bought it from UK ). though i think it's software related , since most of actions are done right on left half of screen , including pushing the very tiny toolbar icons , over there , there is no inaccuracy over there .so it should be something related to program receiving the data to convert it to drawings.
thanks for your response.
any body get an idea about the underlying technology?
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Old 04-26-2009, 06:57 PM   #5
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You can actually produce different accuracy regions by calibrating the stylus differently. Sometimes you can get half the screen working accurately, sometimes the center region and not the edges and so on. Different people angle the stylus and screen in different ways, and result in different calibration, as I think there is a small gap between the surface of the screen and the sensor.

You can try "missing" the calibration points and come up with a calibration setting that best suits your purposes, although there will always be some points that are inaccurate. I don't know if this is because the calibration points are too few, if there is a bug in mapping the points to actual values or a bug in the driver itself. In any case, it should be fixable by software.
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Old 04-27-2009, 09:30 AM   #6
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The Out of the box calibration was better in my newer one than the original. As Grimulkan and others have said, by using the callibratiojn points asa "guide" rather than a definite, the calibration error can be made less severe, however the whole callibration scheme needs either more points or a complete revamp in my opinion.

Calibration on an actual Wacom pad ie on my MAC or PC, never appears as an issue, calibrating just using 3 points on my old Psion 5 and Psion Netbook is not a problem so why is the DR so difficult?

It may be more obvious to some than others, but as I use by default a quad style template for all my notes etc (I draw lots of vectors and graphs) it is very clear that I have to keep well in from the edges to get anything like "accurate" pointing.
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Old 04-29-2009, 10:32 AM   #7
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thanks both of you , now on a different note , why can't i use merge option when i put the SD card in usb reader? it is always disabled ( gray ) , and even when i select a PDF file which i'm sure i have written something on it , it is still inactive
does DR put your written material somewhere else than the PDF itself? in metadata?
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Old 04-30-2009, 10:26 AM   #8
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Originally Posted by KingDani View Post
thanks both of you , now on a different note , why can't i use merge option when i put the SD card in usb reader? it is always disabled ( gray ) , and even when i select a PDF file which i'm sure i have written something on it , it is still inactive
does DR put your written material somewhere else than the PDF itself? in metadata?
I can't comment on the first question (not a windows user), but as to the second question, the scribbles are not written on the PDF but in a file named metadata.db in the same directory as the PDF. That means there is no good reason why you shouldn't be able to merge scribbles with the SD card in a reader. OTOH, the irex reader itself can act as a card reader, so why do you need to bother with a separate reader?
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Old 04-30-2009, 12:32 PM   #9
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On the original topic, is there any speculation as to why there is a calibration issue? I've looked over gtktscal, and it appears to store linear mapping parameters (from Wacom sensor data space to screen resolution space), based on a 5 point calibration system.

Increasing the number of points, IMHO, should not change things much. It looks like there are strange non-linearities when you draw on the screen, I've got the screen edges and the interior to match perfectly while .5-1cm away from the edge there is a mismatch. Anyone else observe this? If this is true, then the actual mapping of Wacom data to the screen is non-linear.

I wonder why this is (and find this a little hard to believe), I've used the Intuos line and I've never had calibration problems. Unfortunately, gtktscal dumps the linear parameters (X/Y shift and X/Y scale, along with X/Y swap for rotation) directly using low level hardware calls, so I don't think we can change this. More calibration points while sticking to a linear map will not do the trick, if the Wacom spits out non-linear data.

Fortunately, one should be able to write a software map on top of the hardware calibration, say, by providing multiple points to calibrate and then using separate linear maps for small parts of the screen (approximating any non-linearities with piecewise linear maps). Just thinking aloud.
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Old 04-30-2009, 01:24 PM   #10
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Grimulkan,
that matches what I find and my understanding of what others find. Provided you are 0.5 - 1cm away from the edges, the calibration is consistent. Closer and it goes pear shaped in a non linear manner.

I have no idea why as it doesn't happen on my wacom drawing pad. It is unfortunate that more points may not help, it wold have been more use to mask the screen so you do not find these non-linearities, maybe I'll get some masking tape
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Old 04-30-2009, 02:29 PM   #11
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[...] I have no idea why as it doesn't happen on my wacom drawing pad.
My concern exactly. I'm either mistaken, or there is something wrong with the hardware. Perhaps the Wacom sensor is flawed, but really, these guys are experts at this sort of stuff, I see no reason why everyone would get a flawed sensor. Maybe we all got stuck with a poor batch . Its also possible that whatever hardware/algorithm applies the calibration is flawed and doesn't apply the linear map correctly. All this sounds funny though, I really wonder whats going on.

I've tried modifying gtktscal to move the calibration crosses around, use more crosses etc., but there are always mismatch errors. Perhaps this mismatch also exists on Wacom drawing tablets, but we just don't notice it because we can't see what we draw. No idea, but again, unlikely. I'm sure mismatches in something like the Cintiq would raise hell among its fan base.

A shame, good calibration with good drawing software and pressure sensing opens out an entire new use for the DR, and it beats the daylights out of the Cintiq in terms of portability.
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