Unterschiede

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--- modellingcomponents:filter [2020/03/13 09:40] – [oneeuro] oliver
+++ modellingcomponents:filter [2020/07/06 10:46] – [interpolation] oliver
@@ Zeile 214: / Zeile 214: @@
 ==== oneeuro====
+This is a simple lowpassfilter especially usefull for filtering humon motion data.
+To minimize jitter and lag when tracking human motion, the two parameters (**minCutOffFrequency** and **beta**) can be set using a simple two-step procedure.
+First beta is set to **0** and **minCutOffFrequency** to a reasonable middle-ground value such as **1 Hz**. Then the body part is held steady or moved at a very low speed while **minCutOffFrequency** is adjusted to remove jitter and preserve an acceptable lag during these slow movements (decreasing **minCutOffFrequency** reduces jitter but increases lag, **minCutOffFrequency** must be **> 0**).
+Next, the body part is moved quickly in different directions while **beta** is increased with a focus on minimizing lag. First find the right order of magnitude to tune beta, which depends on the kind of data you manipulate and their units: do not hesitate to start with values like 0.001 or 0.0001. You can first multiply and divide beta by factor 10 until you notice an effect on latency when moving quickly. Note that parameters **minCutOffFrequency** and **beta** have clear conceptual relationships: if high speed lag is a problem, increase beta; if slow speed jitter is a problem, decrease minCutOffFrequency.
 ^ Attribute ^ Default ^ Unit ^ Description ^ Required ^
 ^ samplingFrequency | 120 | Hz | | No |
 ^ minCutOffFrequency | 5 | Hz | | No |
-^ beta | 0 |  | | No |
+^ beta | 1 | Hz | | No |
 ^ dCutOffFrequency | 0 | Hz | | No |
@@ Zeile 224: / Zeile 232: @@
   * Casiez G., Roussel N., et.al. 1EUR Filter (2012). CHI'12, the 30th Conference on Human Factors in Computing Systems
+==== resampling ====
+Resampling with simple linear inper/extrapolation.
+^ Attribute ^ Default ^ Unit ^ Description ^ Required ^
+^ inFrequency | 120 | Hz | | No |
+^ outFrequency | | Hz | | Yes |
+If outFrequency > inFrequency the more frames at the end are cut, else the unavailable frames at the end are filled with NaN.
+==== interpolation ====
+Interpolation NaN/Inf-values with different possible methods.
+^ Attribute ^ Default ^ Description  ^
+^ method | linear | Posible methods are dividedDifference, linear, loess, neville and spline. |
+^ Method ^ References ^
+^ loess | Locally weighted regression and smoothing scatterplots, W.S. Cleveland, Journal of the American Statistical Association, Vol. 74, No. 368 (Dec., 1979), pp. 829-836. |
+^ neille | Introduction to Numerical Analysis, ISBN 038795452X, chapter 2. |
+^ dividedDifference | Introduction to Numerical Analysis, ISBN 038795452X, chapter 2. |
+NaN-values at the end of the timeserie can not be interpolated.
 ===== Adding filters via external "Math-Engines" like Matlab =====