Latest Contributions by MelitaKennedy

Hmmm, I've done this type of thing many times and if both transformation definitions are set up properly, it works fine. You can see small differences if the rotation parameters are large (over 9" or so) because changing the signs is an approximation. But 140 m sounds like the transformation isn't occurring at all. Some difference in the GCS definitions between what's defined in the transformation and the data or data frame GCS? Melita ... View more

A transformation is always an approximation, so unless a target layer was created by using the same transformation, you will likely see differences. There will also be differences if positions were re-surveyed--a transformation is unlikely to match the new values. So it's not really that the source/target ellipsoids are different, that's just a part of the whole thing. ... View more

At minimum, the data frame's coordinate system would have to be unknown, because ArcMap will 'wrap' or clip data to the equivalent of 360 degrees, or the valid area of use of a projected coordinate system. ... View more

Are you also switching the source/target GCS? ... View more

If you're using the Create Custom Geographic Transformation tool or the New Transformation dialog in ArcMap, you only need to define it in one direction. In fact, it's very slightly more accurate to define the transformation as-given, because then the software can invert the transformation's rotation matrix (more necessary when the rotation values are relatively large). If, for some reason, you do need the parameters for the opposite direction, simply change the signs so: dx(m) = -89.5 dy(m) = -93.8 dz(m) = -123.1 rot(x) = 0 rot(y) = 0 Rot(z) = +0.156 Scale = +1.200 Melita ... View more

There should be no effect. Both projections are well-defined, and I consider them 'lossless'. Yes, there could be some very small movements in the coords, but well below data accuracy (like 5-6th or more decimal place). It's possible you might lose data between them. Mercator is chopped off near the poles, so if you had data there, it would get clipped out. Yes, web Mercator uses a sphere, but it's all being handled internally, and when data is unprojected back to lat/lon you get the original lat/lon values. Melita ... View more

This is just a guess, but are all the data using the same coordinate system? And more importantly, is the GPS data using a foot-based projected coordinate system? Melita ... View more

Hi, You're getting the right coordinates. Northern hemisphere UTM zones have a Y/northing origin at the equator so any data below there will have negative Y values. Southern hemisphere UTM zones have a Y origin at the equator too, but add a false northing of 10000000 m. That means all Y coordinates in the southern hemisphere will be positive. Points above the equator will have Y values larger than 10 million meters. Melita ... View more

Just taking a stab here--IRasterInfo::Extent? (I don't work with rasters at the ArcObjects level) ... View more

Oops, I had the resampling methods backwards! Thanks for correcting me, and I'm glad that you solved your problem. Melita ... View more

I'm sorry, I should have posted about this earlier. Make sure the tool (or geoprocessing settings) is using nearest neighbor. And, more importantly, the cell size is 30m. The difference between WGS84 and NAD83 in the contiguous US (48 states) is about a meter. I wouldn't bother reprojecting the raster. Use its property page in ArcCatalog or the Define Projection tool to set it to NAD83. Melita ... View more

If you email him, use telcordia, not telcoridia! ... View more

Hi Nate, I'm sorry that I wasn't clearer in the earlier message. Use the Define Projection tool or the data's property page in ArcCatalog to change the coordinate system NAD83 UTM Zone 18N. Or you could just clear the coordinate system--make it unknown first. Add it and the other layer to ArcMap. Set the data frame to use NAD83 UTM 18N. If the State Plane data lines up with the point layer (with an unknown coordinate system), you've confirmed that the point layer is using UTM 18N. If a layer has no coordinate system, ArcMap can't do anything to it except display it. ArcMap can't project it to a new coordinate system. It can project layers with a known coordinate system. So you try setting the data frame's coordinate system to what you think the unknown data is in. Melita ... View more

Hi Nate, Just going by the coordinates, I would guess a UTM zone, either 17North or 18North. Because the easting values get pretty small, I think it's 18N. Melita ... View more

There have been other posts about Calibri like: http://forums.arcgis.com/threads/17743-Calibri-Font-issues-in-PDF-after-ArcMap-Export There are a few possible solutions, but nothing that works everywhere. Melita ... View more