In un messaggio del Friday 18 September 2009, Max Ringler ha scritto: > Are there any known issues with projections and/or map units and the home > range plugin? > > When running MCP and kernel analyses, the original point coordinates of my > data seem to get rounded to the next lower meters (decimal digits are > discarded). Accordingly the MCP shapes are "somewhat" correct in shape, but > positioned way off the orignal points - same for kernels. > > My project has meters as map unit and the projects and shapefiles > projection is +proj=utm +zone=22 +ellps=WGS84 +datum=WGS84 +units=m > +no_defs. >
AFAIK (Clement, any feedback?), since the home range plugin uses adehabitat as backend, there should be no issues both with projection (adehabitat is somewhat of "projection-agnostic") and "decimals". Keep in mind that, since you're working with a metric CRS (i.e. UTM zone 22) the figures are in meters, and the "decimals" you're losing are in fact _centimeters_, and normally (either with VHF or GPS) a spatial resolution level at the tenth of meters is normally accepted. Such a precision (down to the centimeter) should be necessary if you're working on small species (insects? shrews?), but normally one doesn't look at decimals in a metric CRS... About the "way off" effect... I smell datum shift problems. Are you visualizing the results in some GIS that handles projection poorly or there is some flaw in how you specify your CRS? Hope this Helps -- Cum tacent, clamant. When they are silent, they shout. -Cicero ----------------------------------------------------------- Damiano G. Preatoni, PhD Unità di Analisi e Gestione delle Risorse Ambientali Dipartimento Ambiente-Salute-Sicurezza Università degli Studi dell'Insubria Via J.H. Dunant, 3 - 21100 Varese (ITALY) tel +39 0332421538 fax +39 0332421446 http://biocenosi.dipbsf.uninsubria.it/ ICQ: 78690321 jabber: [email protected] skype: prea.net ----------------------------------------------------------- Please consider the environment before printing this email Please do not send attachments in proprietary formats http://www.gnu.org/philosophy/no-word-attachments.html Use the UNI CEI Standard ISO/IEC 26300:2006 ----------------------------------------------------------- O< stop html mail - http://www.asciiribbon.org
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