Latest Contributions by MelitaKennedy

"The World from Space" uses the orthographic projection. The "light rays" are hitting the globe as parallel "lines" from an infinite perspective (unlike say Stereographic where the perspective point is on the globe opposite the center point of the plane). Vertical near-side perspective has its perspective point at some distance above the globe, but not at infinity. It's more like the view from a satellite. ... View more

Hi, I don't know what's happening, and I haven't used parcel fabrics. However, I do recognize those numbers that you're seeing. Min X -35666000 Min Y: -30006900 They're the default minimum xy extent/domain values for EPSG:32100 (NAD83 State Plane Montana (meters)). (and the same with the min Z: -100000) I wouldn't expect to see those values unless the feature dataset/class was empty or somehow data was getting placed at that location. Melita ... View more

Possibly set the geoprocessing environment NoData to PROMOTION. It's in the raster storage section. Based on the help, and if I'm understanding it correctly, that may do it. In the help, search for "nodata environment" (without quotes). Melita ... View more

Is there a transcription error in the conversion value?? It should be 3.28083333333333. In meters, you have values at 5 and 6 places even before crossing into decimals, so you need to use a conversion value that matches the desired precision, and probably has at least 1 or 2 extra digits. IProjectedCoordinateSystem2 has PutLinearAndAngularUnits method. That might work. Melita ... View more

What you should do now is define the districts data as Accra Ghana Grid using the layer's property page in ArcCatalog or the Define Projection tool. Tom is correct that the spheroid-based GCS/datum of the first set of data could cause problems later. If you continue to work at a relatively small scale, any offsets (correct or not) due to this incorrect definition won't be noticable. My guess is that the first set of data came through ArcInfo workstation at some point as coverages or grids. ArcInfo Workstation uses a different 'projection engine'. If the datum isn't set, it defaults to Clarke 1866. When that definition is then converted to a shapefile or feature class, you get GCS_Clarke_1866. Because the rest of the definition doesn't match Ghana Grid, it's hard to say if the data is really based on Accra or Leigon or something else. If you have some location where it's easy to overlay features to see if they line up, you might try modifying the coordinate system by changing Clarke 1866 to Accra (leave everything else the same) and see how they line up. If they're offset, try Leigon, set the data frame to WGS84, and set the geographic/datum transformations to convert from Accra and Leigon. Melita ... View more

In 9.3, we didn't have a NAD 1983 UTM zone 13N that uses US survey feet. We have added one in 10.1 (WKID = 4433) but you would need to create a custom definition. You could create a .prj file that contains the new definition and create the coordinate system from that. You could also convert your input data from feet to meters and use the standard UTM zone. Melita ... View more

One thing I noticed when I looked up Ghana coordinate systems, and that led me to ask whether the first set could be overlaid over other data, is that there's a version that uses a "Gold Coast foot". It certainly looks like the layer is 1/3 the size of the other data! Leave it undefined. Add and the other data to ArcMap. Try setting the data frame's coordinate system to Accra Ghana Grid and see if they line up. You should get a gcs/datum warning message. Melita ... View more

The 2nd extent looks very similar to the first. What happens if you redefine (not reproject) the 2nd set to use the same coordinate system? If that doesn't work. Can you overlay the first set (that's using Ghana TM) with a 3rd set of data like general country boundaries? The Ghana TM definition that you have doesn't match other definitions that I've seen for Ghana data. Melita ... View more

For my map, I am using an ESRI basemap (WGS 1984) onto which I layer a NAD 83 layer (ie: roads) via a feature service. On top of these 2 data layers, I have a graphics layer. When I draw something (ie: highlight a road) on the graphics layer via C#, the (x1,y1) and (x2,y2) are correctly provided wrt to the location of road in my NAD 83 system but are actually drawn in Europe as the graphics layer is working in the spatial reference of the basemap (WGS 1984). So the items are drawn correctly but instead of using NAD 83 for measurements, they use the basemap's projection. I think I got it. The base map is in WGS 1984 Web Mercator Auxiliary Sphere aka WKID 3857, not WGS84 (the feature service is NAD83 3TM and is being reprojected to the base map's coordinate system). You'll need to reproject your 3TM coordinates before display. Melita ... View more

In this, I am not speaking officially for Esri (hey, I handle map projections, not geocoding), but I used the Wayback Machine (web.archive.org) to check a random earlier version of the page. The rate was 80 credits per 1000 geocodes in April 2013. April 2013 version of the Geocoding page of ArcGIS Online ... View more

So that means there is no way to reproject a base map into 3TM and view all of North America (coast to coast)? If the answer is no, is there a way I can work around this problem? My current issue is that if I draw something on the graphics layer in North America, it's actually visible in Western Europe. Thanks, That's correct about 3TM. Transverse Mercator was designed for relatively narrow north-south strips. Improvements in the actual algorithms used has made it more able to be used for wide areas but the feature distortion is quite great. Depending on the web service type, you may need a coordinate system with a well-known ID, so a custom definition is probably out. However, why not use a conic projection for North America?  I'm afraid I don't understand your statement about graphics layer items visible in Western Europe. They're not placed correctly? Or...? Melita ... View more

It looks to me like the data is passing through a UTM zone at some point. The longitude range is 90 degrees, and we restrict UTM zones to +/-45 from the central meridian. But the graphic is not using UTM. ... View more

My guess is that the feature class has a spatial reference that includes a geographic coordinate system. The default minimum x value in this case is -400 which is why -120 and the +11million values work (the allowed maximum  x value is very large). Or there's no coordinate system set so the spatial reference default values are just not small enough to allow the -11million value. Let's see if I can install this...if you are using the shapes.gdb sample and the cities feature class, its spatial reference is using a geographic coordinate systems, NAD 1983. It looks like you want to store, web Mercator, maybe? EPSG:3857? You may need to create a new feature class with that coordinate system first. Melita ... View more

Not a programmer! But don't you have the CheckInExtension and CheckOutExtension methods switched? Melita ... View more

A couple of reasons for large vertex counts-- 1. Part of the boundary follows a water feature 2. Even long, "straight" lines shouldn't be only two point lines if you want to reproject the features. ArcGIS doesn't densify data as it reprojects the features. Straight lines may be curves in the new coordinate system. Melita ... View more