> > The effects of spatial reference systems on interpolations and accuracy > are minimal, and lat and long can be used.
Fair enough, thanks for sending the references. But, as far as I know, the kriging functions in R still don't accept lat/long. On Mon, Feb 19, 2018 at 8:54 PM, Li Jin <jin...@ga.gov.au> wrote: > The effects of spatial reference systems on interpolations and accuracy > are minimal, and lat and long can be used. Please see the following studies > for details. > > Jiang, W., Li, J., 2013. Are Spatial Modelling Methods Sensitive to > Spatial Reference Systems for Predicting Marine Environmental Variables, > 20th International Congress on Modelling and Simulation: Adelaide, > Australia, pp. 387-393. > Jiang, W., Li, J., 2014. The effects of spatial reference systems on the > predictive accuracy of spatial interpolation methods. Record 2014/01. > Geoscience Australia: Canberra, pp 33. http://dx.doi.org/10.11636/ > Record.2014.001. > Turner, A.J., Li, J., Jiang, W., 2017. Effects of Spatial Reference > Systems on the Accuracy of Spatial Predictive Modelling along a Latitudinal > Gradient, 22nd International Congress on Modelling and Simulation: Hobart, > Tasmania, Australia, pp. 106-112. > > > -----Original Message----- > From: R-sig-Geo [mailto:r-sig-geo-boun...@r-project.org] On Behalf Of > Dominik Schneider > Sent: Wednesday, 14 February 2018 3:21 AM > To: Stefano Sofia > Cc: r-sig-geo@r-project.org > Subject: [DKIM] Re: [R-sig-Geo] Interpolating snowfall values on a Digital > Elevation Model > > You can't use a lat/long coordinate system when kriging because the > concept of distance is ambiguous. Convert all your data a UTM grid like you > had in your first post and it should work. > > Another note, It looks like you are working at 0.01 deg which is on the > order of 1km resolution so you may find other covariates such as aspect, > slope, and wind sheltering/exposure, terrain roughness for estimating snow > on the ground useful. see some of the earliest papers by Carroll, Cressie, > and Elder. > > Carroll, S. S., and N. Cressie (1996), A comparison of geostatistical > methodologies used to estimate snow water equivalent, *JAWRA Journal of the > American Water Resources Association*, *32*(2), 267–278, > doi:10.1111/j.1752-1688.1996.tb03450.x. > > Carroll, S. S., and N. Cressie (1997), Spatial modeling of snow water > equivalent using covariances estimated from spatial and geomorphic > attributes, *Journal of Hydrology*, *190*(1-2), 42–59. > > Balk, B., and K. Elder (2000), Combining binary decision tree and > geostatistical methods to estimate snow distribution in a mountain > watershed, *Water Resources Research*, *36*(1), 13–26, > doi:10.1029/1999WR900251. > > Erxleben, J., K. Elder, and R. Davis (2002), Comparison of spatial > interpolation methods for estimating snow distribution in the Colorado > Rocky Mountains, *Hydrological Processes*, *16*(18), 3627–3649, > doi:10.1002/hyp.1239. > > Erickson, T. A., M. W. Williams, and A. Winstral (2005), Persistence of > topographic controls on the spatial distribution of snow in rugged mountain > terrain, Colorado, United States, *Water Resour. Res.*, *41*(4), W04014, > doi:10.1029/2003WR002973. > > > On Tue, Feb 13, 2018 at 3:45 AM, Stefano Sofia < > stefano.so...@regione.marche.it> wrote: > > > Dear Daniel and list users, > > I tried to follow the instructions but I encountered two kinds of errors. > > This is a reproducibile code: > > > > ------------------------------------------------------------ > > --------------------------------------------------- > > library(automap) > > library(ggplot2) > > library(gstat) > > library(raster) > > library(rasterVis) > > library(rgdal) > > library(maptools) > > > > ## LOADING DEM > > ita_DEM <- getData('alt', country='ITA', mask=TRUE) > > crs(ita_DEM) <- "+init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs > > +ellps=WGS84 +towgs84=0,0,0" > > #ita_DEM <- as(ita_DEM, "SpatialGridDataFrame") > > str(ita_DEM) > > > > ## LOADING RAINFALL DATA > > rain_data <- data.frame(Cumulata=c(11.8, 9.0, 8.0, 36.6, 9.4), > > Long_Cent=c(12.61874, 12.78690, 12.96756, 13.15599, 13.28157), > > Lat_Cent=c(43.79447, 43.85185, 43.76267, 43.03470, 43.08003), > > Altitude=c(112.20, 42.93, 36.14, 747, 465)) > > > > stations <- data.frame(rain_data$Long_Cent, rain_data$Lat_Cent) > > rain_data <- SpatialPointsDataFrame(stations, rain_data, > > proj4string=CRS("+init=epsg:4326")) > > stations <- SpatialPoints(stations, > > proj4string=CRS("+init=epsg:4326")) > > > > ## EXTRACT THE ELEVATION VALUES TO MY POINTS > > rain_data$ExtractedElevationValues <- extract(x=ita_DEM, y=stations) > > > > ## CREATE GRID FOR KRIGING OUTPUT > > minx <- rain_data@bbox[1,1] > > maxx <- rain_data@bbox[1,2] > > miny <- rain_data@bbox[2,1] > > maxy <- rain_data@bbox[2,2] > > pixel <- 0.01 > > grd <- expand.grid(x=seq(minx, maxx, by=pixel), y=seq(miny, maxy, > > by=pixel)) > > coordinates(grd) <- ~x+y > > gridded(grd) <- TRUE > > proj4string(grd) <- CRS("+init=epsg:4326") > > > > ## KRIGING: autoKrige(YourMeasurements ~ YourExtractedElevationValues, > > YourMeasurementLocations, TargetGrid) OK_snow <- autoKrige(Cumulata ~ > > rain_data$ExtractedElevationValues, > > rain_data, grd) > > ------------------------------------------------------------ > > ------------------------------------------------------------------- > > > > The error I get is: > > Error in autoKrige(Cumulata ~ rain_data$ExtractedElevationValues, > > rain_data, : > > Either input_data or new_data is in LongLat, please reproject. > > input_data: +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs > > +ellps=WGS84 +towgs84=0,0,0 > > new_data: +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs > > +ellps=WGS84 +towgs84=0,0,0 > > > > but I did pay attention to have the same reference system in > > rain_data, drg and the Digital Elevation Model. > > > > Moreover, if I impose the class of the DEM to SpatialGridDataFrame > > when I extraxt the elevation points from the DEM I get the following > error: > > Error in (function (classes, fdef, mtable) : > > unable to find an inherited method for function ‘extract’ for > > signature ‘"SpatialGridDataFrame", "SpatialPoints"’ > > Calls: extract -> <Anonymous> > > > > > > Would you please somebody help to show me where is my mistake? > > > > Thank you for all your attention > > Stefano > > > > (oo) > > --oOO--( )--OOo---------------- > > Stefano Sofia PhD > > Area Meteorologica e Area nivologica - Centro Funzionale Servizio > > Protezione Civile - Regione Marche Via del Colle Ameno 5 > > 60126 Torrette di Ancona, Ancona > > Uff: 071 806 7743 > > E-mail: stefano.so...@regione.marche.it > > ---Oo---------oO---------------- > > ________________________________________ > > Da: R-sig-Geo [r-sig-geo-boun...@r-project.org] per conto di Daniel > > Knitter [knit...@geographie.uni-kiel.de] > > Inviato: lunedì 12 febbraio 2018 9.16 > > A: r-sig-geo@r-project.org > > Oggetto: Re: [R-sig-Geo] Interpolating snowfall values on a Digital > > Elevation Model > > > > ...sorry, I missed one step: you need to extract the elevation values > > to your points via extract function from the raster package: > > > > YourPoints$YourExtractedElevationValues <- extract(x = DEM, y = > > YourPoints) > > > > autoKrige(YourMeasurements ~ YourExtractedElevationValues, > > YourMeasurementLocations, TargetGrid) > > > > > > Sorry for spamming. > > > > Best, > > Daniel > > > > On Mon, 12 Feb 2018 08:03:41 +0000 > > Stefano Sofia <stefano.so...@regione.marche.it> wrote: > > > > > Dear list users, > > > I have to produce rainfall maps. I know how to create a > > > (bi-dimensional) > > grid and interpolate rainfall values (from automatic rain gauges) on > > that grid using Kriging: > > > > > > myinterpolation <- autoKrige(myrainfall_cumulate ~ 1, rain_data_UTM, > > mygrid) > > > > > > In reality I am dealing with snowfall values on mountain regions, > > > and in > > this case altitude is an important factor, the use of a Digital > > Elevation Model might make the difference. > > > Looking in the web I found some important material about accessing > > elevation data in R with the "elevatr" package (by J.W.Hollister), I > > am reading it. > > > My concern would then be to interpolate snowfall values on a Digital > > Elevation Model. Did somebody already use R for these kinds of > > calculations? Could somebody share with me some useful hints? > > > > > > Thank you for your attention > > > Stefano Sofia > > > > > > > > > (oo) > > > --oOO--( )--OOo---------------- > > > Stefano Sofia PhD > > > Area Meteorologica e Area nivologica - Centro Funzionale Servizio > > > Protezione Civile - Regione Marche Via del Colle Ameno 5 > > > 60126 Torrette di Ancona, Ancona > > > Uff: 071 806 7743 > > > E-mail: stefano.so...@regione.marche.it > > > ---Oo---------oO---------------- > > > > > > ________________________________ > > > > > > AVVISO IMPORTANTE: Questo messaggio di posta elettronica può > > > contenere > > informazioni confidenziali, pertanto è destinato solo a persone > > autorizzate alla ricezione. I messaggi di posta elettronica per i > > client di Regione Marche possono contenere informazioni confidenziali e > con privilegi legali. > > Se non si è il destinatario specificato, non leggere, copiare, > > inoltrare o archiviare questo messaggio. Se si è ricevuto questo > > messaggio per errore, inoltrarlo al mittente ed eliminarlo > > completamente dal sistema del proprio computer. Ai sensi dell’art. 6 > > della DGR n. 1394/2008 si segnala che, in caso di necessità ed > > urgenza, la risposta al presente messaggio di posta elettronica può > essere visionata da persone estranee al destinatario. > > > IMPORTANT NOTICE: This e-mail message is intended to be received > > > only by > > persons entitled to receive the confidential information it may contain. > > E-mail messages to clients of Regione Marche may contain information > > that is confidential and legally privileged. Please do not read, copy, > > forward, or store this message unless you are an intended recipient of > > it. If you have received this message in error, please forward it to > > the sender and delete it completely from your computer system. > > > > > > -- > > > This message was scanned by Libra ESVA and is believed to be clean. > > > > > > > > > [[alternative HTML version deleted]] > > > > > > _______________________________________________ > > > R-sig-Geo mailing list > > > R-sig-Geo@r-project.org > > > https://urlsand.esvalabs.com/?u=https%3A%2F%2Fstat.ethz.ch% > > 2Fmailman%2Flistinfo%2Fr-sig-geo&e=52342f8a&h=f7d4a649&f=y&p=y > > > > > > -- > > > > Dr. Daniel Knitter > > CRC1266 -- Scales of Transformation > > Project A2 "Integrative Modeling of Socio-Environmental Dynamics" > > > > Christian-Albrechts-Universität zu Kiel Department of Geography > > Physical Geography -- Landscape Ecology and Geoinformation > > Ludewig-Meyn-Str. 14, room 109 D - 24118 Kiel, Germany > > > > Phone: +49 431 880 2941 > > Email: knit...@geographie.uni-kiel.de > > > > ________________________________ > > > > AVVISO IMPORTANTE: Questo messaggio di posta elettronica può contenere > > informazioni confidenziali, pertanto è destinato solo a persone > > autorizzate alla ricezione. 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