raster

The code below produces two boxes on my image. I am planning to analyze pixels within those boxes further. I want to put a condition that if along an edge of a box, there is a black color (or a similar color such as grey) pixel then don't proceed. How can i specify such condition? In below example, in the case of the red square I don't want to proceed further as it has black pixels at the top right hand corner. While I would like to proceed in the case of green square as it doesn't have a black color pixel along it's edge. library(raster) r1 <- brick(system.file("external/rlogo.grd", package=

I noticed some weird behavior when resizing the plot window. Consider library(sp) library(rgeos) library(raster) rst.test <- raster(nrows=300, ncols=300, xmn=-150, xmx=150, ymn=-150, ymx=150, crs="NA") sap.krog300 <- SpatialPoints(coordinates(matrix(c(0,0), ncol = 2))) sap.krog300 <- gBuffer(spgeom = sap.krog300, width = 100, quadsegs = 20) shrunk <- gBuffer(spgeom = sap.krog300, width = -30) shrunk <- rasterize(x = shrunk, y = rst.test) shrunk.coords <- xyFromCell(object = rst.test, cell = which(shrunk[] == 1)) plot(shrunk) points(shrunk.coords, pch = "+") If you resize the window, plotted

I have a shapefile downloaded from the worldwildlife.org for the terrestrial ecoregions of the world. The file can be loaded here: http://worldwildlife.org/publications/terrestrial-ecoregions-of-the-world . It comes as a standard shape file and I would like to do two things with it. First: take the shapefile from my local directory and clip it to an extent of eastern North America (ext= extent (-95, -50, 24, 63)) # Read shapefile using package "maptools" eco_shp <- readShapeLines("F:/01_2013/Ecoregions/Global/wwf_terr_ecos.shp", proj4string=CRS("+proj=utm +zone=33 +datum=WGS84")) # Set the

In back face culling you may either use the face normals to see if the face is pointing away from the camera of you may do some technique with if the triangle is drawn clock wise or counter clock wise. I am confused about this technique with the clockwise. It seems like with this method, the ordering of the vertex data that gets sent to the graphics card decides whether it is facing towards or away from the camera. I don't see how this makes sense because the camera can be looking in any direction, it's as if the vertex data would have to change based on the camera position and that is

I want to perform a moving window regression on every pixel of two raster stacks representing Band3 and Band4 of Landsat data. The result should be two additional stacks, one representing the Intercept and the other one representing the slope of the regression. So layer 1 of stack "B3" and stack "B4" result in layer 1 of stack "intercept" and stack "slope". Layer 2 of stack B3 and stack B4 result in layer 2,.... and so on. I already came along the gwr function, but want to stay in the raster package. I somehow know that focal must be included in order to set my moving window (which should be

I would like to use the original colortable of a >>georeferenced raster image<< (tif-file) as coloured scale in a map plotted by ggplot/ggplot2 . Due to not finding an easier solution, I accessed the colortable -slot from the legend -attribute of the loaded raster image (object) raster1 like so: raster1 <- raster(paste(workingDir, "/HUEK200_Durchlaessigkeit001_proj001.tif", sep="", collapse="")) raster1.pts <- rasterToPoints(raster1) raster1.df <- data.frame(raster1.pts) colTab <- attr(raster1, "legend")@colortable Ok, so far so good. Now I simply need to apply colortable as a colored scale to

Can anyone clarify if the GDI StretchBlt function for the workstation Win32 API performs bilinear interpolation for scaling to both larger and smaller images for 24/32-bit color images? And if not, is there a GDI ( not GDI+) function that does this? The SetStretchBltMode fn has a setting HALFTONE which is documented as follows: HALFTONE Maps pixels from the source rectangle into blocks of pixels in the destination rectangle. The average color over the destination block of pixels approximates the color of the source pixels. I've seen references (see follow-up to first answer) that this performs

I quite like the look and feel of ggplot2 and use them often to display raster data (e.g facetting over timesteps for time-varying precipitation fields is very useful). However, I'm still wondering whether it is easily possible to bin the continuous raster values into discrete bins and assign to each bin a single colour , that is shown in the legend (as many GIS systems do). I tried with the guide = "legend" , and breaks arguments of the scale_fill_gradient option. However these affect just the legend on the side of the graph, but the plotted values are still continuous. library(ggplot2) data