question
Dear all, I am trying to calculate an area from a picture. I think I can use Spatial Analyst but I am not sure how to do it. I have a picture from the wing of a bird, and from there, I want to calculate the area of a white patch. The picture is with a scale bar. Is there a way to do that? There is not spatial information on the picture. Thanks in advance, Ana
On Sep 29 2012, r-sig-geo-request at r-project.org wrote:
Send R-sig-Geo mailing list submissions to r-sig-geo at r-project.org To subscribe or unsubscribe via the World Wide Web, visit
https://stat.ethz.ch/mailman/listinfo/r-sig-geo or, via email, send a message with subject or body 'help' to r-sig-geo-request at r-project.org You can reach the person managing the list at r-sig-geo-owner at r-project.org When replying, please edit your Subject line so it is more specific than "Re: Contents of R-sig-Geo digest..." Today's Topics: 1. Re: plotting holes of esri shape files (Edzer Pebesma) 2. Re: basic question about plotKML (Struve,Juliane) 3. Re: basic question about plotKML (Edzer Pebesma) 4. Re: basic question about plotKML (Struve,Juliane) 5. Re: Create a raster brick from a netcdf using all levels (Robert J. Hijmans) 6. Re: NaN / NA values in SpatialPixelDataFrame conversion (Robert J. Hijmans) 7. Re: Error when trying to extract values for points in a SpatialPointsDataFrame (Robert J. Hijmans) ---------------------------------------------------------------------- Message: 1 Date: Fri, 28 Sep 2012 13:18:18 +0200 From: Edzer Pebesma <edzer.pebesma at uni-muenster.de> To: "r-sig-geo at r-project.org" <r-sig-geo at r-project.org> Subject: Re: [R-sig-Geo] plotting holes of esri shape files Message-ID: <5065877A.5090805 at uni-muenster.de> Content-Type: text/plain; charset=ISO-8859-1 Stefan, with the help of http://www.stat.auckland.ac.nz/~paul/R/Paths/MurrellPaths.pdf I corrected this in spplot. To run it, you'd need to compile from source on svn, or source this in your R session: https://r-forge.r-project.org/scm/viewvc.php/*checkout*/pkg/sp/R/spplot.R?root=rspatial or wait for the next release on CRAN (due soon, I hope). spplot now also supports holes in polygons when the polygons are the main object to plot, contain holes, and something in the background should shine through. Building on the example in https://stat.ethz.ch/pipermail/r-sig-geo/2012-September/016116.html p1 = spplot(mask, col.regions='lightgrey', sp.layout = list("sp.grid", as(dem_ascii, "SpatialGridDataFrame"), col = bpy.colors(), first = TRUE), main = "spplot of mask") p2 = spplot(dem_ascii, col.regions=bpy.colors(), main = "spplot of dem", sp.layout = list("sp.polygons", mask, fill = 'lightgray', first = FALSE)) png('spplot.png', 600, 600) print(p1, split = c(1,1,1,2), more = TRUE) print(p2, split = c(1,2,1,2)) dev.off() gives http://ifgi.uni-muenster.de/~epebe_01/spplot.png as output. Mind the legends. With best regards, On 09/20/2012 10:32 AM, sluedtke wrote: Dear friends, am trying to overlay a polygon data set as a SpatialPolygonDateFrame to an existing plot. The data set has a hole in the middle, and I do not want to have any filling in there. If a check the shape in a GIS, everything looks fine, but using the following commands to do the plot, the hole is filled. That is the code I am using, the data is attached. Thanks in advance! Stefan ################################################################################################ library(sp) library(rgdal) library(raster) library(latticeExtra) ############################################################################################### #read the DEM from the ASCII format dem_ascii=raster(readGDAL("./zerafshan_mod_dem.asc")) ############################################################################################### # read additional data for printing mask=readOGR("./", "mask_zerafshan") ############################################################################################### #plot this stuff plot_dem=spplot(dem_ascii, col.regions=terrain.colors(400), colorkey=list(width=1, space="right"))+ layer(sp.polygons(mask,fill="lightgray")) print(plot_dem) ################################################################################################ mask_zerafshan.dbf (110 bytes) <http://r-sig-geo.2731867.n2.nabble.com/attachment/7580992/0/mask_zerafshan.dbf> mask_zerafshan.prj (143 bytes) <http://r-sig-geo.2731867.n2.nabble.com/attachment/7580992/1/mask_zerafshan.prj> mask_zerafshan.shp (173K) <http://r-sig-geo.2731867.n2.nabble.com/attachment/7580992/2/mask_zerafshan.shp> mask_zerafshan.shx (150 bytes) <http://r-sig-geo.2731867.n2.nabble.com/attachment/7580992/3/mask_zerafshan.shx> zerafshan_mod_dem.asc (1M) <http://r-sig-geo.2731867.n2.nabble.com/attachment/7580992/4/zerafshan_mod_dem.asc> -- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/plotting-holes-of-esri-shape-files-tp7580992.html Sent from the R-sig-geo mailing list archive at Nabble.com. _______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
PhD student Evolutionary Ecology Group Department of Zoology University of Cambridge