Generate a coordinate list for a zig-zag survey

The coordinate list is generated in degrees decimal degree format (dd.ddd), with Southern hemisphere denoted by negative numbers. Transect length are specified in km and bearings in degress where North 0 deg, East 90 deg, South 180 deg and West 270 deg.

Usage

zigzagSurvey(
  startLon,
  startLat,
  lineLengthkm,
  startBearingdeg,
  rotationdeg,
  numOfLines,
  proj4string = CRS("+proj=longlat +datum=WGS84"),
  unrotated = FALSE
)

Arguments

startLon

start longitude of survey.

startLat

start latitude of survey.

lineLengthkm

transect line length in km.

startBearingdeg

Bearing of each transect in degrees.

rotationdeg

rotation angle for entire survey pattern.

numOfLines

Number of transects.

proj4string

projection string of class CRS-class

unrotated

FALSE return rotated coordinates TRUE list of rotated and unrotated coordinates.

Value

Geographical coordinates of start and end of line positions. unrotated=TRUE list of rotated and unrotated coordinates

See also

zigzagSurvey

Author

Martin Cox martin.cox@aad.gov.au

Examples

if (FALSE) {
coords=zigzagSurvey(startLon=-100,startLat=-60,lineLengthkm=2,
startBearingdeg=30,
rotationdeg=10,numOfLines=11)
plot(0,0,xlim=range(coords[,1]),ylim=range(coords[,2]),type='n',
xlab='Longitude, deg',ylab='Latitude, deg')
arrows(x0=coords[1:(nrow(coords)-1),1], y0=coords[1:(nrow(coords)-1),2], 
      x1 = coords[2:nrow(coords),1], y1 = coords[2:nrow(coords),2])
text(coords,row.names(coords),cex=0.6)
points(coords[1,1],coords[1,2],col='blue',pch=17,cex=2)
points(coords[nrow(coords),1],coords[nrow(coords),2],col='blue',pch=15,cex=2)
legend('topright',c('Beginning','End'),col='blue',pch=c(17,15))
#Use unrotated=TRUE and check coordinates in the- 
#-returned coordinate list object are identical:
coordL= zigzagSurvey(startLon=-100,startLat=-60,lineLengthkm=2,
startBearingdeg=30,
rotationdeg=0,numOfLines=11,unrotated=TRUE)
identical(coordL[[1]],coordL[[2]])
#display rotated and unrotated coordinates"
coordL= zigzagSurvey(startLon=-100,startLat=-60,lineLengthkm=2,
startBearingdeg=30,
rotationdeg=5,numOfLines=11,unrotated=TRUE) 
coords=coordL$unrotatedGeogs; coordsRotate=coordL$rotatedGeogs
plot(0,0,xlim=range(c(coords[,1],coordsRotate[,1])),
ylim=range(c(coords[,2],coordsRotate[,2])),type='n',
xlab='Longitude, deg',ylab='Latitude, deg')
arrows(x0=coords[1:(nrow(coords)-1),1], y0=coords[1:(nrow(coords)-1),2], 
      x1 = coords[2:nrow(coords),1], y1 = coords[2:nrow(coords),2])
arrows(x0=coordsRotate[1:(nrow(coordsRotate)-1),1], 
y0=coordsRotate[1:(nrow(coordsRotate)-1),2], 
      x1 = coordsRotate[2:nrow(coordsRotate),1], 
      y1 = coordsRotate[2:nrow(coordsRotate),2],col='blue')
legend('bottomleft',c('Unrotated','Rotated'),lty=1,col=c(1,'blue'))
}