[GIS] Comparing two DEMs with RMSE

demraster

I am relatively new to GIS. I am trying to compare a DEM that I developed through photos from an aerial drone and a DEM that we developed through traditional surveying methods.

Exactly how would I get the RMSE? I saw some similarly asked questions that explained how to use R to get it, but I am very unfamiliar with any sort of coding. Is there anyway to get the RMSE through Spatial Analyst or other already available tools?

Best Answer

There are numerous ways to examine the differences between two surfaces. A starting point would be:

Subtracting the two DEMs shows the differences as a map, which can indicate areas where one or both are erroneous.
Scatterplot with one on the X-axis and one on the Y-axis, to show correlation.
Calculate co-variance, RMSE, bimodality etc between the two datasets.
Creating contours from both layers and analyze those statistically.

Also, you could read Comparison of three contour lines or What is a good metric for mapping accuracy for ideas.

Related Solutions

[GIS] Comparing two Digital Elevation Models (DEMs) from LAS files

How to compare two Digital Elevation Models (DEMs) in R.

#-------------------------------------------------------------------------
#Creating a reproducible example

library(raster)

  #simulating raster_1

  f = system.file("external/test.grd", package="raster")
  DEM_1 = raster(f)

  #simulating raster_2

  DEM_2 = DEM_1
  # replacing values from raster_1 to create a new raster sample (raster_2)
    DEM_2[(DEM_2>500 & DEM_2<900)] = 550
    DEM_2[(DEM_2>200 & DEM_2<300)] = 500

#-------------------------------------------------------------------------
# Comparison 1 (DEM_3 resulted from subtracting DEM_2 from DEM_1)

  DEM_3 = DEM_1 - DEM_2

    par(mfrow=c(1,3))

    plot(DEM_1, main = "DEM_1")
    plot(DEM_2, main = "DEM_2")
    plot(DEM_3, main = "DEM_3 = DEM_1 - DEM_2")

      dev.off()

enter image description here

#-------------------------------------------------------------------------
#Comparison 2 (histogram)

  hist(DEM_1, prob=T, main="DEM_1", xlab="")
  hist(DEM_2, prob=T, main="DEM_2", xlab="")
  hist(DEM_3, prob=T, main="DEM_3 = DEM_1 - DEM_2", xlab="")

    par(mfrow=c(1,1))

  standard_deviation = sd(c(as.matrix(DEM_3)),na.rm=T)

    dev.off()

enter image description here

#-------------------------------------------------------------------------
#comparison 3 (RMSE)

  library(hydroGOF)

  DEM_1_matrix = c(as.matrix(DEM_1))
  DEM_2_matrix = c(as.matrix(DEM_2))

  rmse = rmse(DEM_1_matrix,DEM_2_matrix)
  rmse
  [1] 135.3675 # this is the root mean squared error (RMSE) result.

See @whuber's answer on Comparing two TINs created using ArcGIS for Desktop? for a theoretical insight about this issue.

Best Answer

Related Solutions

[GIS] Comparing two Digital Elevation Models (DEMs) from LAS files

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