10 Visualization

Transform to 3D, visualization and interpretation of results

Handling 3D data sets

  • What kind of object do we have here?

  • How can work with it?

  • How can we manipulate it and extract secondary information?

# general path set up
myDir <- file.path("C:/Users/yourname/Documents/radarkurs/Grid-dir2-Rawdata")
setwd(myDir) 

# load library
library(RGPR)

#read one single line in one object
grid_file<-readGPR(dsn="FILE____001.DZT", verbose = F)


#load all lines from data set
grid_lines<- file.path(paste0("FILE____", sprintf("%03d", 1:46), ".DZT"))


#create GPR survey object with all lines
grid <- GPRsurvey(grid_lines, verbose = FALSE)

#set default grid coordinates
setGridCoord(grid) <- list(xlines = seq_along(grid),
                           xpos   = seq(0,
                                        by = 0.2,
                                        length.out = length(grid)),
                           ylines = NULL,
                           ypos   = NULL)

# apply filters
grid <- papply(grid,
             prc = list(estimateTime0 = list(method = "coppens", w = 2),
                        # "NULL" because we take the default
                        time0Cor = NULL,
                        dewow = list(w = 3),
                        gain = list(type = "agc", w = 1.2) #,
                        # traceStat = list(w = 20, FUN = mean),
                        # envelope = NULL)
             ))
#create cube object
SXY <- interpSlices(grid, dx = 0.05, dy = 0.05, dz = 0.05, h = 6)

3D Visualization

#new library RGL R-openGL
#please install first!
library(rgl)

#setting the properties of a cube
c3d <- cube3d(color="green", alpha=0.1)  

#what kind of object is it?
c3d   

#plot the cube
#an interactive window opens- try and use your cursor on the cube!
shade3d(c3d)   

#save a quick image
# works with many plot functions when an interactive window was opened
rgl.snapshot("cubes3d.png")
image of cube using 3D plot in R 
#plot the single lines together in an interactive 3D window
#note: this function is from the package RGPR again!
plot3DRGL(grid)

# plot only selected lines 
plot3DRGL(grid[1:3])
GPR cube top plotted in R
GPR cube front plotted in R 
#plot single line 
*** Class GPR ***
plot(grid_line)
GPR cube plotted in R 
#plot type GPR survey -> plotting the current position of GPR lines in the summarizing object
*** Class GPRsurvey ***
plot(grid)
GPR cube plotted in R 
#plot type GPR cube

be careful: very long processing time !!!

*** Class GPRcube ***
plot(SXY)
GPR cube plotted in R

3D object structure

#single line object
grid_file

#the str() function reveals all stored information within the data object we are handling in R
# all objects in R can be accessed with this function
str(grid_file)

#the standard symbols in R to access information within any object are "@" and "$"
#tipp: use the "tab" button on your keyboard to display the options
grid_file

grid_file@version
grid_file@data
grid_file@traces

#GPR survey object
grid

grid@names
grid@ntraces
grid@coords
grid@coords$FILE____001 #oder
grid[[1]]
grid[1]

#GPR cube
SXY

SXY@x
SXY@y
SXY@depth
SXY@data