ajai_ubkv

projection problems

Discussion created by ajai_ubkv on Sep 13, 2010
Sir/Madam,

My study area lies between 85-86 degree E and 23-24 degree N in India.I digitise the contour lines at 5 m interval giving Geo(Lat/long) projection.I am using arcswat which is interfaced with Arcgis9.3.1. SWAT needs its inputs (DEM,LULC and soil map) to be in projected coordinate system.

I made DEM by view-create TIN-3D Analyst-convert-TIN to raster. I projected this raster dataset which is DEM in polyconic projection. Polyconic projection requires False eastings/northing, center meridian and latitude of origin. I have kept False eastings/northing as 0.0, center meridian as the average of top left and right coordinate sof map i.e. in degree decimal. I took latitude of origin as bottom left of my DEM in Degree decimal. Sometimes after projection, I used to get different lat/long such 84 degree.

Again I am using TM images for land use. The data was projected in UTM (45N). I changed the projection from UTM to polyconic by arc catelogue (through properties). The extent of land use map was different than DEM so the center of meridian and lat of origin.

I kept cell size as 30, 30 but column and rows are not same. My DEM shows pixels as continuous signed integer with 32 bit and LULC showing as discrete unsigned integer with 8 bit.

Problem, First I am not able open both the map in one data frame. It is not overlaying in single window. It is opening in single window but at distance.

While overlaying in SWAT, it is howing spatial geometrics should be same.

I am struggling hard to do it. Please advise.

Regards

Ajai Singh

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