Latest Contributions by MelitaKennedy

Hi Megan, Earlier you said that the data ended up in the wrong hemisphere so here are two things to check. Are the longitude and latitude fields labeled correctly? If you're using x and y for the field names, x = longitude and y = latitude. Also, if the data is in the US, the longitude values must be negative. Melita ... View more

I think you want to look at GeometryEngine:Project. If you can, you should try to use coordinate systems (spatial references) that are known to the system and that have a well-known ID. For instance, WGS84 is 4326. Melita ... View more

Hi Brad, We're trying to match the EPSG Geodetic Parameter Dataset. 29900 was deprecated by them back in 2001. We didn't follow until much later. I don't see what the reason for the name change was (beyond correcting it for what's actually used), although the area of use also changed. We also changed the original name of 29900 from "Irish_National_Grid" to "TM65_Irish_Grid" around ArcGIS 9.0 or 9.1. Melita Std Disclaimer: I'm on the subcommittee that maintains the EPSG Dataset. ... View more

Do you mean you want to change the data's coordinate system so that the data is a different location? Ex. Move a raster that represents London, England and have it show up on the Rhine instead? If so, you could georeference the raster again. Or if it's in a projected coordinate system like UTM, redefine the coordinate system to a different UTM zone, or otherwise modify the projection parameters of the existing PCS definition. Melita ... View more

hi i am new to work with arcgis. i want to project a raster data to a coordinate system. can anyone tell to find which projected coordinate system suits for a particular area. my study area covers 77-78E and 8-9N Hello, It looks like you're working in the same area as India Zone IV (4) or UTM zone 43N. The first uses Lambert conformal conic, and the 2nd uses transverse Mercator. Both area conformal so they maintain shapes and angles, not areas so depending on what you want to do, they may or may not be appropriate. You can find the list of supported coordinate systems in the ArcGIS installation folder, Documentation, projected_coordinate_system.pdf. Another place which is easier to search, is http://www.epsg-registry.org and then check to see whether we support it or not. Disclaimer: I am a member of the subcommittee that maintains the EPSG registry. Melita ... View more

My guess for the area calculation is that the coordinate system is a geographic one: latitude/longitude and thus degree-based so it doesn't make sense to calculate "square degrees". Try reprojecting the data to a projected coordinate system that preferably uses an equal area-based projection like Albers or Lambert azimuthal. If the area doesn't have to be that accurate, use the local UTM or state plane zone (both use conformal projections which maintain shapes, not areas). Melita ... View more

Hello Misa, There are a few GK zone 7 files. Projected coordinate systems, Gauss-Kruger Europe    Pulkovo 1942 Adj 1958 3-Degree GK Zone 7    Pulkovo 1942 Adj 1983 3-Degree GK Zone 7 Pulkovo 1942     Pulkovo 1942 3 Degree GK Zone 7 The third one is the least likely one, but I don't know which of the other two is more likely. Melita ... View more

The scale distortion for Mercator based on a sphere (which web Mercator is) varies as 1/cos(latitude). The equation when based on an ellipsoid is a little more complicated. So if at 40N, 1.3054. Melita ... View more

It's VB.Net, but this works for me in VS. It does not include the ControlPrecision setting nor setting the tolerance and resolution values. The other thread references a very old help topic. A more up-to-date one is here: Creating a Custom Projected Coordinate System Another thread using C#: http://forums.esri.com/Thread.asp?c=93&f=1170&t=124093&mc=11#826802 It's older, and I haven't tested that version for a while. Here's one that worked for me.         Dim pSR As ISpatialReference3         pSR = Nothing         Dim t As Type = Type.GetTypeFromProgID("esriGeometry.SpatialReferenceEnvironment")         Dim obj As System.Object = Activator.CreateInstance(t)         Dim pSRF As ESRI.ArcGIS.Geometry.ISpatialReferenceFactory3 = obj          ' Create a projection, GeographicCoordinateSystem, and unit using the factory.         Dim projection As IProjectionGEN = TryCast(pSRF.CreateProjection(CInt(esriSRProjectionType.esriSRProjection_Sinusoidal)), IProjectionGEN)         Dim geographicCoordinateSystem As IGeographicCoordinateSystem = pSRF.CreateGeographicCoordinateSystem(CInt(esriSRGeoCSType.esriSRGeoCS_WGS1984))         Dim unit As ILinearUnit = TryCast(pSRF.CreateUnit(CInt(esriSRUnitType.esriSRUnit_Meter)), ILinearUnit)         ' Get the default parameters from the projection.         Dim parameters As IParameter() = projection.GetDefaultParameters()         ' Create a PCS using the Define method.         Dim projectedCoordinateSystemEdit As IProjectedCoordinateSystemEdit = New ProjectedCoordinateSystemClass()         Dim Name As Object = "Newfoundland"         Dim [Alias] As Object = "NF_LAB"         Dim abbreviation As Object = "NF"         Dim remarks As Object = "Most Eastern Province in Canada"         Dim usage As Object = "When making maps of Newfoundland"         Dim geographicCoordinateSystemObject As Object = TryCast(geographicCoordinateSystem, Object)         Dim unitObject As Object = TryCast(unit, Object)         Dim projectionObject As Object = TryCast(projection, Object)         Dim parametersObject As Object = TryCast(parameters, Object)         ' Note: Alias is a reserved keyword in VB .NET. To use it as a variable name, encase it in brackets [ ].         projectedCoordinateSystemEdit.Define(Name, [Alias], abbreviation, remarks, usage, geographicCoordinateSystemObject, unitObject, projectionObject, parametersObject)         pSR = projectedCoordinateSystemEdit Melita ... View more

Check out Select by Attribute in ArcMap. You should be able to select all but the Alaska and Hawaii counties. At that point, you can export the layer into a new feature class using the data, export data dialog (right click the layer in the table of contents). In ArcMap, Selection menu, choose Select by Attribute. In the "Select * from counties" box, put "STATE_NAME" <> 'Alaska' AND "STATE_NAME" <> 'Hawaii' Melita ... View more

Although it's a lot of data to download, there are ready-to-use-in-ArcMap packages available at PIGWAD, http://webgis.wr.usgs.gov/. See the August 8 entry: "Aug 8, New (v 1.8) Mars Global GIS Bundle (5.6GB) (link)". If you follow the link, there are complete and regional sets. Melita ... View more

I think you just need to define the coordinate system (projection) for the CAD file. You'll want to use NAD 1927 which is in geographic coordinate systems, North America. (depending on your version, it might be called North American 1983) See Defining a coordinate system for a CAD dataset. Melita ... View more

I'm sorry about the delay in responding. It looks like the first dataset has the wrong coordinate system definition. One thing I look for is what are the extent values? Are they similar to the false easting/false northing values? In this case, the false easting/northing values are 200000.0 and 300000.0, but the Y/northing values are 4.5 million. I think this dataset may be using a UTM zone instead, possibly 29N (N = north). Melita ... View more

Hi, You're using the tool. The wizard is accessed through ArcMap and you have to add it onto a toolbar. You'll probably not going to like this, but they both buffer fine on my not-a-high-end XP machine running 10.1 SP1. A check geometry on the simpleline shapefile ran clean, no problems. Melita fyi, Curtis: The dissolve bug appears to be connected to almost-zero-length segments in the data which is why it doesn't happen on all feature classes. ... View more