waveformlidar (version 1.2.0)

waveformgrid: waveformgrid

Description

The function allows you to project raw waveforms into 2d grids (can be xy, yz, and xz) with self defined resolution. For the values of each grid, four kinds of values were available to be used: the total number of intensity in each grid, maximum intensity of the grid, mean intensity of the grid, and total intensity of the grid.

Usage

waveformgrid(
  hpc,
  waveform = NULL,
  geo = NULL,
  quan = NULL,
  res = c(0.8, 0.8),
  method = "HPC"
)

Arguments

hpc

The hyper point cloud generated from the raw waveform data with hyperpointcloud function or the data with the same structure as the hyperpointcloud object.

waveform

The raw waveform data with only intensities.

geo

The reference geolocation that corresponds to the raw waveform data which requres has the same row as the waveform data. At least three colomns should be assigned: original x, y and first return reference bin location (fr,leading edge 50 You can see detailed description of the columns in geotransform.

quan

The quantile of intenisty in the given grid or voxel. Defalut is NULL.

res

The grid size with x and y spatial resolution. Default is 0.8*0.8, res=c(0.8,0.8).

method

There are two methods c("HPC","Other") to project the waveforms into the 2d surface. Default ("HPC") is to use the HPC as the input data. The waveform and geo will be NULL. "Other" is to use the raw waveform and corresponding reference geolcation data to generate the intensities in each grid, and hpc should be NULL.

Value

A dataframe with 7 columns including geolocation (center of the grid) and intensities. Specifically, these 7 columns are "index","cx","cy","length_maxi_meani_totali.1","length_maxi_meani_totali.2", "length_maxi_meani_totali.3","length_maxi_meani_totali.4").

index

The index of the grid

cx

The mean x of the grid center

cy

The mean y of the grid center

intensity.length or value.length

The number of intensity in the grid. intensity.length is for the HPC method and value.intensity for the others

intensity.maxi or value.maxi

The maximum intensity of waveforms in the grid

intensity.meani or value.meani

The mean intensity of waveforms in the grid

intensity.totali or value.totali

The total intensity of waveforms in the grid

...

Percentile intensity based on the quan

By assigning differnt columns as x and y, the users can project waveforms into the xy, xz, yz surfaces.

References

Tan Zhou, Sorin Popescu, Lonesome Malambo, Kaiguang Zhao, Keith Krause. From LiDAR waveforms to Hyper Point Clouds: a novel data product to characterize vegetation structure. Remote Sensing 2018, 10(12), 1949; https://doi.org/10.3390/rs10121949

Examples

# NOT RUN {
data(return)  ###import raw return waveforms
data(geo)  ###import corresponding reference geolocation
##if your geo data didn't the same column names as the follwoing one, you need to change it to
#it to the same column names. One thing you need to figure out is the corresponding column numbers
colnames(geo)[1:8]<-c("x","y","z","dx","dy","dz","or","fr")
###at least you should know which columns corresponding to x,y and fr before run the waveformgrid
##using the raw data
grid_re<-waveformgrid(waveform=return,geo=geo,res=c(0.8,0.8),method = "Other")

##using the hpc object
hpc<-hyperpointcloud(waveform=return,geo=geo)

hpcgrid<-waveformgrid(hpc=hpc,res=c(1,1))
# }