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. 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. > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo Geoscience Australia Disclaimer: This e-mail (and files transmitted with it) is intended only for the person or entity to which it is addressed. If you are not the intended recipient, then you have received this e-mail by mistake and any use, dissemination, forwarding, printing or copying of this e-mail and its file attachments is prohibited. The security of emails transmitted cannot be guaranteed; by forwarding or replying to this email, you acknowledge and accept these risks. ------------------------------------------------------------------------------------------------------------------------- _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
