How to convert lidar format las to data.frame?

Question

Lidar data is simply 3d coordinates, usually in las file format. Сontent example

library(rgdal)
library(raster)
library(tmap)
library(tmaptools)
library(lidR)
library(RStoolbox)
las_cat <- readLAScatalog("C:/1/078-638.las")
summary(las_cat)
opt_chunk_size(las_cat) <- 500
plot(las_cat, chunk_pattern = TRUE)
las_cat
#> class       : LAScatalog (v1.2 format 1)
#> extent      : 637999, 638240.5, 6077999, 6079999 (xmin, xmax, ymin, ymax)
#> coord. ref. : NA 
#> area        : 483081.1 units²
#> points      : 3.68 million points
#> density     : 7.6 points/units²
#> density      : 5.6 pulses/units²
#> num. files  : 1

Is there a way to get point coordinates in a typical data.frame for R? As an example we can use data from this http://data.wvgis.wvu.edu/elevation/. Also, is there a way to get the angle of reflection, the number of reflections in the data.frame from the lidar file?

Answer 1

Please find below one possible solution to get a data.table,data.frame with all the information. You can use as.data.frame() to get a pure data.frame but a data.table is a data.frame

Reprex

NB: I used a .las dataset built in the lidR library as it is more convenient.

• The example dataset from lidR

library(lidR)

LASfile <- system.file("extdata", "example.laz", package="rlas")
las <- readLAS(LASfile)

summary(las)
#> class        : LAS (v1.0 format 1)
#> memory       : 21.2 Kb 
#> extent       : 339002.9, 339015.1, 5248000, 5248001 (xmin, xmax, ymin, ymax)
#> coord. ref.  : NAD83 / UTM zone 17N 
#> area         : 16 m²
#> points       : 30  points
#> density      : 1.88 points/m²
#> density      : 1.62 pulses/m²
#> File signature:           LASF 
#> File source ID:           0 
#> Global encoding:
#>  - GPS Time Type: GPS Week Time 
#>  - Synthetic Return Numbers: no 
#>  - Well Know Text: CRS is GeoTIFF 
#>  - Aggregate Model: false 
#> Project ID - GUID:        00000000-0000-0000-0000-000000000000 
#> Version:                  1.0
#> System identifier:        LAStools (c) by rapidlasso GmbH 
#> Generating software:      las2las (version 201011) 
#> File creation d/y:        343/2011
#> header size:              227 
#> Offset to point data:     323 
#> Num. var. length record:  1 
#> Point data format:        1 
#> Point data record length: 28 
#> Num. of point records:    30 
#> Num. of points by return: 26 4 0 0 0 
#> Scale factor X Y Z:       0.001 0.001 0.001 
#> Offset X Y Z:             6e+05 6500000 0 
#> min X Y Z:                339002.9 5248000 973.145 
#> max X Y Z:                339015.1 5248001 978.345 
#> Variable Length Records (VLR):
#>    Variable Length Record 1 of 1 
#>        Description: by LAStools of rapidlasso GmbH 
#>        Tags:
#>           Key 1024 value 1 
#>           Key 3072 value 26917 
#>           Key 3076 value 9001 
#>           Key 4099 value 9001 
#> Extended Variable Length Records (EVLR):  void

• Suggested code

payload(las)

• Output

#>          Z  gpstime Intensity ReturnNumber NumberOfReturns ScanDirectionFlag
#> 1  975.589 269347.3        82            1               1                 1
#> 2  974.778 269347.3        54            1               1                 1
#> 3  974.471 269347.3        27            2               2                 1
#> 4  974.025 269347.3        55            2               2                 1
#> 5  974.298 269347.3       117            1               1                 0
#> 6  974.985 269347.3        81            1               1                 0
#> 7  975.182 269347.3        84            1               1                 1
#> 8  974.434 269347.3       104            1               1                 1
#> 9  974.159 269347.3        91            1               1                 1
#> 10 973.145 269347.3        99            1               1                 1
#> 11 976.739 269347.5        87            1               1                 1
#> 12 976.823 269347.5        83            1               1                 1
#> 13 977.227 269347.5        87            1               1                 1
#> 14 975.873 269347.5        87            1               1                 1
#> 15 975.782 269347.5       107            1               1                 1
#> 16 975.353 269347.5        76            1               1                 1
#> 17 974.704 269347.5       113            1               1                 1
#> 18 977.170 269347.5        64            1               1                 0
#> 19 977.757 269347.5        89            1               1                 0
#> 20 978.212 269347.5        98            1               1                 0
#> 21 978.309 269347.5        50            1               2                 0
#> 22 974.816 269347.5        31            2               2                 0
#> 23 978.345 269347.5        51            1               2                 1
#> 24 974.824 269347.5        32            2               2                 1
#> 25 978.014 269347.5        85            1               1                 1
#> 26 977.781 269347.5        94            1               1                 1
#> 27 976.455 269347.5        78            1               1                 1
#> 28 976.313 269347.7        71            1               1                 1
#> 29 975.735 269347.7        75            1               1                 1
#> 30 975.674 269347.7       106            1               1                 1
#>    EdgeOfFlightline Classification Synthetic_flag Keypoint_flag Withheld_flag
#> 1                 1              1          FALSE         FALSE         FALSE
#> 2                 0              1          FALSE         FALSE         FALSE
#> 3                 0              1          FALSE         FALSE         FALSE
#> 4                 0              1          FALSE         FALSE         FALSE
#> 5                 0              1          FALSE         FALSE         FALSE
#> 6                 0              1          FALSE         FALSE         FALSE
#> 7                 1              1          FALSE         FALSE         FALSE
#> 8                 0              1          FALSE         FALSE         FALSE
#> 9                 0              1          FALSE         FALSE         FALSE
#> 10                0              1          FALSE         FALSE         FALSE
#> 11                1              1          FALSE         FALSE         FALSE
#> 12                0              1          FALSE         FALSE         FALSE
#> 13                0              1          FALSE         FALSE         FALSE
#> 14                0              1          FALSE         FALSE         FALSE
#> 15                0              1          FALSE         FALSE         FALSE
#> 16                0              1          FALSE         FALSE         FALSE
#> 17                0              1          FALSE         FALSE         FALSE
#> 18                0              1          FALSE         FALSE         FALSE
#> 19                0              1          FALSE         FALSE         FALSE
#> 20                0              1          FALSE         FALSE         FALSE
#> 21                0              1          FALSE         FALSE         FALSE
#> 22                0              2          FALSE         FALSE         FALSE
#> 23                1              1          FALSE         FALSE         FALSE
#> 24                1              2          FALSE         FALSE         FALSE
#> 25                0              1          FALSE         FALSE         FALSE
#> 26                0              1          FALSE         FALSE         FALSE
#> 27                0              1          FALSE         FALSE         FALSE
#> 28                1              1          FALSE         FALSE         FALSE
#> 29                0              2          FALSE         FALSE         FALSE
#> 30                0              1          FALSE         FALSE         FALSE
#>    ScanAngleRank UserData PointSourceID        X       Y
#> 1            -21       32            17 339002.9 5248001
#> 2            -21       32            17 339003.0 5248000
#> 3            -21       32            17 339002.9 5248000
#> 4            -21       32            17 339002.9 5248000
#> 5            -21       32            17 339003.6 5248000
#> 6            -21       32            17 339003.5 5248000
#> 7            -21       32            17 339003.6 5248000
#> 8            -21       32            17 339003.7 5248000
#> 9            -21       32            17 339003.6 5248000
#> 10           -21       32            17 339003.7 5248000
#> 11           -22       32            17 339009.6 5248001
#> 12           -22       32            17 339009.5 5248001
#> 13           -22       32            17 339009.2 5248000
#> 14           -22       32            17 339009.4 5248001
#> 15           -22       32            17 339009.3 5248000
#> 16           -22       32            17 339009.3 5248000
#> 17           -22       32            17 339009.3 5248000
#> 18           -22       32            17 339009.5 5248000
#> 19           -22       32            17 339009.5 5248000
#> 20           -22       32            17 339009.5 5248000
#> 21           -22       32            17 339009.6 5248000
#> 22           -22       32            17 339010.7 5248001
#> 23           -22       32            17 339009.6 5248000
#> 24           -22       32            17 339010.6 5248001
#> 25           -22       32            17 339009.5 5248000
#> 26           -22       32            17 339009.4 5248000
#> 27           -22       32            17 339009.7 5248000
#> 28           -22       32            17 339015.1 5248000
#> 29           -22       32            17 339015.1 5248000
#> 30           -22       32            17 339015.0 5248000

^{Created on 2022-03-18 by the reprex package (v2.0.1)}

Answer 2

If you do not want to play with lidR and want to use bare bone data.frame simply use rlas instead of lidR.

library(rlas)
read.las("C:/1/078-638.las")