# Matching Pixels With Field Book The function uses the raster image of all bands. It generates the limits of the unit and extracts the values of each pixel of the plot n x m units (n, m = 1,2, ...). The function requires the dimensions of the unit observed and the number of units per row (width) and column (length). The result is a table with image information and the characteristics of the experimental unit. ```r imageField(r, Q, ny, nx, dy, dx, start=1, plotting = TRUE, ...) ``` ## Arguments - `r`: raster image - `Q`: References points of de area - `ny`: Number of experimental units along the plot (y axis) - `nx`: Number of experimental units across the plot (x axis) - `dy`: Wide of unit plots - `dx`: Length of unit plots - `start`: Number of the first experimental unit - `plotting`: Overlap the units in the area, TRUE or FALSE - ``...``: Other parameters the plot ## Returns - **parameters**: Parameters of experimental design in precision agriculture - **Qbase**: Image data frame with location in field - **coordinates.EU**: The limits of each experimental unit ## See Also `EUsPoint`, `fixedPoint`, `fourPoint`, `designRaster`, `cassava` ## Examples ```r library(rPAex) data(cassava) r <- terra::rast(cassava, type="xyz") # x11() # terra::image(r) # p<-locator(2) # e<-terra::ext(unlist(p)) e <- terra::ext(287691.9, 287708.6, 8664188, 8664203) rc <- terra::crop(r,e) # Selection of experimental units, p1 and p2 in terra::image(r) p1<-list(x=c(287698.34, 287701.14, 287702.33), y=c(8664200.89, 8664201.65, 8664190.67)) p2<-list(x=c(287701.56, 287704.37, 287705.24), y=c(8664198.68, 8664199.44, 8664191.46)) q1<-fourPoint(p1) q2<-fourPoint(p2) # dimension of the experimental unit dy=1; dx=0.9 op<-par(mar=c(0,0,3,0)) terra::image(rc,main="Selection of experimental units\nCassava crop",axes=FALSE) img1<-imageField(rc, q1, ny=11, nx=3, dy, dx, plotting = TRUE, border="blue",lwd=1) img2<-imageField(rc, q2, ny=8, nx=3, dy, dx, start=34,plotting = TRUE, border="blue",lwd=1) # Spectral data of selected units R<-rbind(img1$Qbase,img2$Qbase) head(R) Q<-agricolae::tapply.stat(R[,2:3],R[,1],mean) text(Q[,2],Q[,3],Q[,1],cex=1) par(op) ```

imageField function