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I want to have different touch and digitizer pen calibration for each orientation of the screen.

The touch settings are not too bad since the location is based on the tip of the finger. It feels a little off, but it could just be my lack of practice with touch screens.

The digitizer pen on the other hand does not use the very tip of the pen for location, but instead, the sensor is about 1/4th to 3/8th of an inch from the tip. So when the screen orientation is changed, the current calibration actually works against the proper location. The more one writes at an angle, the worse it becomes.

If anyone knows of a decent fix that would be great, if not, I would not mind creating a program that looks for a rotation then updates the registry with the proper calibration. Worse case I just have little scripts that I activate manually when ever I change orientation. But, I don't know where those values are located. This was a hell of a lot easier in Linux.

If needed, The computer is a Samsung ATIV Smart PC Pro 700T1C (XE700T1C-A01US) with Windows 8 x64.

Thank you for any little help you can give me,

Will

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Old question, however, I have done some research on my Surface Pro 3, and maybe it's still helpful. Please comment if something is wrong, and check information on other devices.

Some background: There are two problems with digitizers, and thus two kinds of calibration in Windows.

  1. The first one is non-linearity: the location of the pen is not detected exactly, but there is a position dependent offset. This deviations were awful with some devices I had in the past, the NTRIG in my Surface Pro 3 is in fact much better: on the left side of the screen, the deviation is about 0.3 mm (~1/100") horizontally, to the right no deviation is detectable. Some people may call this "calibration not recommended", but in High School in technical drawing a precision of 0.1 mm was expected (with a sharp pencil, I'm 50 years old).

  2. Secondly, the digitizer does not detect the contact point of the pen with the glass, but some point 1 to 2 mm (1/16") from the tip. Thus, if you tilt the pen, the detected spot will move. I will call this effect "parallax".

These two effects are completely independent and have no connection with each other.

The Non-Linearity is corrected by Windows by the LinearityData (stored in the Windows Registry -> Wikipedia). To change it, you first have to clear the calibration data in the Tablet PC dialogue, and then click "Calibrate". You get a 16-point calibration grid; as this is the Linearity correction, you should hit these points with the Pen held exactly perpendicular to the screen.

If you now hit the "calibrate" button in the TabletPC settings again, you see the 4-point calibration. In fact, this is the parallax correction! Hold the pen at your comfortable writing angle, and hit the four points.

Naturally, the Linearity Correction is independent of screen rotation, thus there is only one data set (in the registry).

There are, however, four different parallax correction data sets; you can produce them all by repeating the 4-point calibration in all four screen rotations. Additionally, there seem to be two data sets for landscape with and without keyboard attached. You now have a perfectly calibrated screen in all screen rotations.

There is useful information on techniques for a "better" non-linearity correction here, but also at http://www.surfaceforums.net/threads...-the-pen.5157/ However, it does not seem necessary at my Surface Pro 3. One problem with tabcal.exe is that it creates an entry "LinearityData" in the registry, instead of "UserLinearityData". This overrules "LinearityData", but cannot be deleted with the TabletPC dialogue. One has to use regedit (-> Google) to get rid of it.

I would like to be able to perform the 4-point parallax calibration without the linearity calibration, however, you have to go through linearity to be able to do the parallax. You should be very precise when doing the linearity calibration, or you will actually degrade the linearity: drink no coffee before, and hold year breath.

BTW, I could not locate where Windows 10 stores the parallax correction for NTRIG (Wacom tablets store it at C:\Users[your user name]\AppData\Roaming\WTablet\ISD_Tablet.dat).

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