Arduino reads potentiometer values from 0 to 1023. If you want to use the potentiometer value to drive a number input in Motionbuilder, you have to choose the range you want control over. This means you have a limited range of values to work with.

What if you wanted to use the same potentiometer to drive multiple values? For example you have two cameras, and the pot value controls the fov. You rotate the pot to 512 setting the fov on the first camera. You then switch to modifying the second camera. If the second camera was set to 100, as soon as you rotate the pot the camera will jump from 100 to 511.

Additionally what if you want finer control? Say if you want the full range of the pot to be half of the current range.

The best solution I can think of is using some sort of rotary encoder like the scroll wheel of a mouse. This would be the simplest and easiest way to handle this, however I came up with using a sliding offset when mapping your pot value to the object value.

For this to work you need a pot, and two buttons(Offset, and High Res). When you rotate the pot it adjusts the value mapped between offset and offset + resolution. While holding "offset" when you rotate the pot it adjusts the offset but the value remains the same. While holding "High Res" when you rotate the pot it will adjust the value but the resolution will be half the size it currently is, allowing you to adjust the value with more control. Given your offset = 5, resolution = 10, value= 10, and your pot is at 50% rotating the pot to 0% with "High Res" pressed(multiplying resolution by 0.5) will result in your value being set to 7.5. The same rotation without "High Res" pressed would result in the value being set to 5.

To calculate this you need 4 pieces of information.

• The current value
• The offset. This is the value when your pot value is 0
• The resolution. This added to the offset will be the value when your pot value is 1023
• The Multiplier: This value is used to shrink the resolution

Here is a python example of how to map the values.

class Camera:
	def __init__(self, value, offset, resolution):
		# current value of the camera(Fov for example)
		self.value = float(value)
		# the offset value is mapped to zero on the pot
		self.offset = float(offset)
		# offset + resolution is mapped to 1024 on the pot
		self.resolution = float(resolution)
	
	def mapVal(self, x, mult=1.0, in_min=0, in_max=1023):
		# update the min and max values to map to the pot value
		out_min = self.value - ((self.value - self.offset) * mult)
		out_max = out_min + self.resolution * mult
		# Map the pot value to your number line value
		out = (x - in_min) * (out_max - out_min) / float(in_max - in_min) + out_min
		return out
	
	def updatePotVal(self, value, offset=False, resMult=1.0):
		if offset:
			val = self.mapVal(value, resMult)
			self.offset += self.value - val
		else:
			self.value = self.mapVal(value, resMult)

<p>>>> a = Camera(5, 5, 10)
>>> a.updatePotVal(512)
>>> print a.value, a.offset, a.offset + a.resolution
10.0048875855 5.0 15.0
>>> a.updatePotVal(0, resMult=0.5)
>>> print a.value, a.offset, a.offset + a.resolution
7.50244379277 5.0 15.0
>>> a.updatePotVal(1024, offset=True)
>>> print a.value, a.offset, a.offset + a.resolution
7.50244379277 -2.5073313783 7.4926686217
>>> a.updatePotVal(512)
>>> print a.value, a.offset, a.offset + a.resolution
2.49755620723 -2.5073313783 7.4926686217</p>