Hi Brian, The original tiff file may have been compressed, which would explain why the .ers file blew out. The other possible reason is that the number of cells and columns changed.
wrt the rectification (30MB -> 120MB) this may be due to - the number of cells and columns changed. This can sometimes happen when tranforming to particular projections (not sure if World Mercator is one of them), or the output cellsize is different. You can adjust the cellsize in the geocoding wizard, and it will indicate what the output filesize will be. Hope this helps. cheers Mike > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of Brian Murphy > Sent: Wednesday, 24 July 2002 7:58 AM > To: '[EMAIL PROTECTED]' > Subject: Projection File Size > > > Hi All, > > I have a rectified TIFF image from ArcMap8x. The image was > rectified using > 4 corners (UTM values) from the original raw TIFF image (a > scan (150 dpi) of > a NTS Topo Mapsheet). It was rectified in UTM Nad 27. > I wanted to reproject the image in World Mercator Nad 27, > with the Central > Meridian at -96 West. > > The original TIFF image (256-color with 8.5m pixel) was 12mb in size. > When saved as .ERS file, the size went to 30+mb. > The newly rectified (Mercator 96) image was nearly 4 times > (120MB) the .ERS > file. > The newly saved TIFF image (256-color) (Mercator 96) was 75 MB, while > maintaining the original pixel size (8.5m) value of the > original TIFF image. > I am uncertain why the file sizes of the new .ERS file (and > resulting TIFF > image) were so high. > Does the reprojection procedure normally boost the file size > so much higher, > or are there only certain reprojections that cause this to happen. > I have included the World Mercator 96 info that was used to > provide us with > the new projection (if that indeed will help any). > > Any assistance/suggestions would be appreciated. > > RSVP discussion group AND to this e-mail. > Thanks, > Brian > > ..LIne information from Mercator.dat..... > > proj_name mr96w, > false_north 0, > false_east 0, > scale_factor 1, > centre_merid -1.675516082, > centre_lat 0, > radius 6378206.4, > eccentricity 0.082271854, > flattening 294.9786982, > prime_merid 1 > > > > > ----------------------------------------------------------- > > To make changes to your subscription, please visit our > website, http://www.ermapper.com/technicl/ermapperl/index.htm > > > ----------------------------------------------------------- To make changes to your subscription, please visit our website, http://www.ermapper.com/technicl/ermapperl/index.htm
