Latest Contributions by MelitaKennedy

I want to project a raster from WGS84 Geographic to NameBessel2217 which is the projected coordinate system used in Namibia. The problem i have however is that there are a entire list of possible transformations and i am uncertain which to use. Can anyone offer any advice on which transformation to pick? Thanks Hi, Can you give the details on the target coordinate system? Bessel is a spheroid (ellipsoid), not a datum. EPSG ( http://www.epsg.org and http://www.epsg-registry.org - online version is running slowly right now; the subcommittee is working on the problem) only lists Schwarzeck (although the Cape and Hartebeesthoek probably also apply, but they don't use Bessel ellipsoid) which does use Bessel Namibia. The transformation to use would be Schwarzeck_To_WGS_1984_2. We have a UTM zone based on Schwarzeck. Otherwise, EPSG lists several zones based on Lo22. These use a south-west oriented system that we don't support. I've been told that you can emulate the Lo systems, by using -1 for the scale factor. Melita ... View more

I run ArcMap 9.1. I have some .dwg files without projections that I would overlay on aerial photos. From everything I've read, it seems that the georeferencing toolbar is the best way to accomplish this, but whenever I load the .dwg files into ArcMap, they are not recognized by the toolbar. The toolbar does work because I have used for other types of image files. Can anyone help me out with this one? Thanks. Austin Austin, In 9.1, the georeferencing toolbar didn't support CAD files yet (unless scanned images). Instead you need to identify two pairs of coordinates in the CAD's coordinate system and in the target coordinate system. You can put them into a CADname.wld file: x1_source, y1_source, x1_target, y1_target x2_source, y2_source, x2_target, y2_target If you open the CAD layer's property page (in ArcMap), you can add some transformation information there instead. There's information on this in the help. Here's the web link: http://webhelp.esri.com/arcgisdesktop/9.1/body.cfm?tocVisable=1&ID=222&TopicName=Applying a coordinate transformation to a CAD layer or via your installed help, ArcMap, Creating Maps, Applying a coordinate transformation... Melita ... View more

Hello and thank you in advance. I am still, unfortunately, a little confused on the projection for posting data in Google Earth: I understand that GE and MS apps use a spheroid only model, which is the projection ESRI calls: Geographic Coordinate System, (spheroid-based)  "GCS_WGS 1984 Major Auxiliary Sphere" or Projected Coordinate System (World) "WGS_1984_Web_Mercator" Whereas ESRI uses a spheroid or ellipsoid model, which is the projection ESRI calls: Geographic Coordinate System (World)  "GCS_WGS_1984" or Projected Coordinate System (World) "WGS_1984_Web_Mercator (Auxiliary Sphere)" The instructions in Technical Article ID: 34749 say when using 9.3 SP1 to use the: Predefined Projected Coordinate System (World) "WGS_1984_Web_Mercator" HERE IS MY PROBLEM: When projecting from NAD83 to Projected WGS_1984_Web_Mercator in the toolbox, there is a message that this is an undefined projection, and I can only do it with a double: NAD_1983_To_WGS_1984_5 AND WGS_1984_Major _Auxiliary_Sphere_To_WGS_1984 The same is true (obviously) if I try to project from NAD83 to Geographic GCS_WGS_1984_Major_Auxiliary_Sphere Isn't this exactly the same as just going from NAD_1983_To_GCS_WGS_1984, which is the ESRI model, not the Google Earth or MS (Bing) model, right? In the end, projecting to GCS_WGS_1984 is equivalent to projecting to PCS_WGS_1984_Web_Mercator which is equivalent to projecting to GCS_WGS_1984_Major_Auxiliary_Sphere The only difference is that the denominator of the flattenting ratio for the PCS_WGS_1984_Web_Mercator is infinity instead of 298.257224.   No matter what, the locations lie directly on top of one another and NOT where I can see them (my well points) on the Google Earth image. So, how do folks line up their very locatlized point locations on a Google Earth visualization for their projects/clients? In addition, using the double transform to get to Projected Coordinate System (World) "WGS_1984_Web_Mercator" yields the same projected or local bounding coordinates as Projected Coordinate System (World) "WGS_1984_Web_Mercator (Auxiliary Sphere)" HOWEVER, Google Earth will not import the file "WGS_1984_Web_Mercator (Auxiliary Sphere)"  (says zero features) Why does this happen? HELP!! Nicki Cook Ni Nicki, You're caught in between our transitioning to "WGS_1984_Web_Mercator (Auxiliary Sphere)". Both it and "WGS_1984_Web_Mercator"  will have exactly the same coordinate values for the same location on the Earth. They're just different ways of emulating the coordinate system used by Bing and Google maps when they cache their data. If you access the coordinates as latitude-longitude values, they are WGS84. But what's cached is in a Mercator projection where the math supports a sphere only. For the sphere's radius, they use the semimajor axis (equatorial radius) of WGS84: 6378137.0 meters. So why are there two versions? When we originally made a definition for "Web Mercator", we had only one implementation of Mercator. It contains equations to use with a sphere or a spheroid/ellipsoid. The only way to trigger the sphere equations that are needed is to use a geographic coordinate system (GCS) based on a sphere. We built a custom WGS 1984 Major Auxiliary Sphere for it and defined "WGS_1984_Web_Mercator". Later, we added a new implementation of Mercator that supports a parameter (Auxiliary Sphere Type), which describes how to calculate a sphere's radius from a normal spheroid/ellipsoid-based GCS and use it with the projection. The projection's name is Mercator_Auxiliary_Sphere. Both versions do the same thing, force spherical math. The earlier version, using the custom GCS causes problems because you have to do a geographic (datum) transformation to it, so it's awkward. The 'new' version uses the standard WGS84 definition, so it simplifies the workflow. The version you're using hasn't been updated to support caching your data with the newer "WGS_1984_Web_Mercator (Auxiliary Sphere)". Melita ... View more

Hi Chris, this isn't really an ArcObjects question, well at least my answer isn't.  You can symbolize your layer in ArcMap based on quantities and a proportial symbol.  So if you had a count field in your line feature class defined as a numeric field, you could use that as a quantity.  Then you can set your min and max width and all that good stuff. Given Alexander's answer, I found IProportionalSymbolRenderer in the SDK help. It's in the Carto library. Melita ... View more

bzborow1;18473 wrote: Hi Guys, I'm building a search service to query unprojected attribute data, project it, and deliver the extent back to the client.  The method I'm using works unpredictably.  For are larger land parcels it re-projects perfectly find, but for really small land parcels, quarter sections, it won't reproject using the getEnvelope() method.  Can anyone offer some advice on how I might fix this problem? QUOTE] I am speculating that it could a problem with the resolution/domain values of the target spatialreference (less likely: the tolerance). Perhaps the resolution value is too large and the envelopes are collapsing. Another possibility is that the envelope, after projecting it, is distorted enough that it's collapsing. I think that would be more likely with 'long' sides--they should be densified to reflect what's happening when the data's projected, aren't. Melita ... View more

Thanks very much, Jim! I'm not desperate enough to switch browsers, but that's certainly a possibility. Melita ... View more

We are upgrading SDE from 9.3.1 to 9.3.1(sp1). We downloaded the SDE complete suite but missing the PE.pdb in particular. We could find it in the previous version (e.g. pe-sdk-bin-9.3.1-b1632-windows.zip) for both x32 and x64 platforms. The pdb is important for our development. Thank you so much and we're looking for this file urgently. Eric Eric, Will you contact me at mkennedy at esri dot com? The standard SDKs don't include the pdb (nor debug build) files. There were only two fixes for the projection engine for 9.3.1 SP1. One was for Java: if you tried to retrieve the horizion for several projections, it would crash. The other change was to improve performance when confirming whether two versions British National Grid are the same (we changed the scale factor in 9.2). Melita ... View more

Hi All, I have been trying using IBasicGeoprocessor interface's Intersect method, to create point layer at the point of intersection between the 2 layers.(one is line layer & other is polygon layer) But even after setting outputFeatureClass's shapeType property to esriGeometryPoint, type of output layer is Polygon. Could you please help me in resolving this issue. Thanking you in advance. Regards, Viji When I read the description of IBasicGeoprocessor's Intersect method, it says: [INDENT]Intersect clips the features of a line or polygon layer with features of an overlay polygon layer. The output feature class will have the attributes of both input and overlay layers. [/INDENT] It's never going to return a point feature class. As IBasicGeoprocessor says, you should use the Geoprocessing framework and tools. The Analysis toolbox has an Intersect tool that should do what you want. I haven't used it, so I don't have any sample code. There's a sample in the SDK that may help you get started: http://resources.esri.com/help/9.3/ArcGISDesktop/dotnet/43d8cc77-5193-4ca8-9878-6027782e2bbb.htm Melita ... View more

I have a table with geocoded Lat/Long Values that I want to add as point features to my map. However when I add the table and add X/Y data (Tools-Add X/Y data) the data is added to the map but the projection doesn't match up. I did compare the coordinate systems and they appear to be the same whoever the extent doesn't match up. My Shapefile with the Lat/Long Points has similar values in projected coordinates compared to the decimal degrees which leads me to believe it doesn't project? Here is an example. My Zip Code layer in decimal degrees: West: -117.597982 East: -116.080157 North: 33.511553 South: 32.530161 In projected or local coordinates: Left: 6150765.000000 Right: 6613436.500000 Top: 2129760.000000 Bottom: 1775304.125000 NAD_1983_StatePlane_California_VI_FIPS_0406_Feet And my XY layer that doesn't match: Decimal: West: -136.179977 East: -136.179964 North: 25.945595 South: 25.945576 In projected or local coordinates: Left: -117.388904 Right: -116.371055 Top: 34.517990 Bottom: 32.543795 NAD_1983_StatePlane_California_VI_FIPS_0406 also I tried about everything. If somebody could help me with this it would be GREATLY appreciated. Thank you for posting the reported data extents! The XY layer should be using a geographic coordinate system like NAD 1983, not California VI. You need to tag it with its current coordinate system. ArcMap can project it on the fly to match your other data. If you want to convert it permanently to State Plane, right click the layer in the table of contents and select Data, Export Data. In the export dialog, set it to use the data frame's coordinate system. Melita ... View more

Hello, I am writing an application in C# using the ArcGIS Engine SDK to provide ground elevation information at specified locations.  I'm using a RasterCatalog to store DTED elevation data.  To retrieve the elevation height at a desired location, I create a Surface out of the Dataset in the RasterCatalog that contains the location and then call the get_Z method, passing in the location coordinates.  From a little research I've learned that DTED elevation height information is in reference to the EGM96 geoid model of the earth.  (This model is similar to the one used for the WGS84 geoid model so I consider them interchangeable.)  This process works well but there are times when I am more interested in the the elevation above the WGS84 ellipsoid rather than above the geoid.  I've been told by ESRI representatives that vertical datum conversions are already built into the ArcGIS Engine 9.3.1 SDK in the Projection Engine but I have not been able to locate it.  Has anyone else been able to perform this conversion on a point to point basis? Thanks, cm Hi, The Projection Engine SDK (C or Java) is included with the ArcSDE SDK. The functionality is there to convert values using an EGM96 file. I've attached a C program that can convert EGM96/WGS84 geoid heights to WGS84 ellipsoid heights. Even though it says version 10 in the beginning, it works at 9.3.1. The particular vertical transformation is 10084 ("WGS_1984_To_EGM_1996_Geoid_1"). There are FORTRAN programs to access a geoid file here: http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/egm96.html In the past, some people have converted geoid grid file into a raster and then queried the raster for the conversion value. Melita ... View more