coord_transform: coordinate transformation

In USGS-R/GDopp: processing of ADV data

Description

coord_transform is modified from Transform.m (from http://www.nortek- as.com/en/knowledge-center), which is a Matlab script that shows how velocity data can be transformed between beam coordinates and ENU coordinates. Beam coordinates are defined as the velocity measured along the three beams of the instrument. ENU coordinates are defined in an earth coordinate system, where E represents the East-West component, N represents the North-South component and U represents the Up-Down component.

Note that the transformation matrix must be recalculated every time the orientation, heading, pitch or roll changes.

Usage

coord_transform(trans_matrix, data_v, position_data)

Arguments

trans_matrix	a matrix of tranformation values (static) in 3 x 3 matrix.
data_v	a velocity matrix (a data.frame)
position_data	positional data as a data.frame

Author(s)

Jordan S. Read

References

Lohrmann, Atle, Ramon Cabrera, and Nicholas C. Kraus. Acoustic- Doppler velocimeter (ADV) for laboratory use. In Fundamentals and advancements in hydraulic measurements and experimentation, pp. 351-365. ASCE, 1994.

Examples

trans_data <- c(-0.3462, 0.0869, 2.6611, -0.3252,  2.2522, -1.2607, -0.3616, -2.3228,-1.4019) # trans matrix for example package data
trans_matrix <- matrix(data = trans_data, ncol = 3, byrow = TRUE)
position_data <- data.frame(heading = 358.4, pitch = -1.38, roll = -0.3)
data_v <- data.frame(velocity.X =  c(-0.205, -0.185),
# X is up, Y is along stream, Z is cross stream
velocity.Y = c(-1.5303, -1.5452), velocity.Z = c(0.3747, 0.3763))
ENU <- coord_transform(trans_matrix, data_v, position_data)

USGS-R/GDopp documentation built on May 9, 2019, 6:09 p.m.