Latest Contributions by DavidMedeiros

I'm helping an artist with a project that requires a modified polyconic projection of the world, centered on N America. The artist wants to render globe gores, like the image attached below, but with the center on the US (around 100w 40n). In both ArcMap and ArcGIS Pro I am able to modify the Central Meridian of standard polyconic coordinate system to re center along 100w meridian, but I can't make any changes to the Latitude of Origin to put N America under the center of the north pole. FYI, the artist has another team member who is using Global Mapper to generate the centered globe gores, but is also unable to modify the coordinate system to recenter the map. Any advice on how to change either the coordinate system itself or the input raster (Natural Earth GeoTIF) to get the desired effect is greatly appreciated. ... View more

I'm trying to make a simple animation of a boundary progression over time in ArcGIS Pro. The data are a set of individual layers for a national boundary, each layer is a different time step. In the animation menu I'm setting keyframes, one for each time interval, turning each layer on in secession. In the Timeline window I see the correct keyframe thumbnails, and if I advance the frames manually from the Playback menu they change as expected. But, if I hit play on the Playback menu the screen goes blank and I just see the time slide moving but no map. If I export as a Draft or GIF I get export files with only the basemap showing, my layers are missing. What is going on with my animation? ... View more

I'm working with historical mining maps and trying to visualize mine shafts below the surface in a 3d WebScene. The process in ArcScene is to just apply a negative extrusion to a flat polygon layer relative to an elevation surface. This same process works for positive extrusions in the web scene, but as soon as a negative value is used the polygon disappears. Underground navigation is on and the base map is set to [none] with the default ground set to partially transparent.  Is the My Scene app not able to visualize underground or subsurface features?  ... View more

I'm helping a colleague with a historic map of a portion of the Nevada gold mining regions from mid 1800's. The map shows claim foot prints along with some very general information for mine shafts (entrance location, general layout in plan view only, and elevations for top, bottom and every junction along the shaft). We want to visualize the mines in 3d to some extent and have pulled the map and an elevation surface into ArcScene. One idea I have for a basic sub surface visualization is to show the mine shafts as 3d features (cylinders or rectangular prisms) that descend below the surface and angle away in main direction of the shaft. We don't have detailed profile schematics, but the top and bottom shaft elevations combined with plan view locations for the top and bottom of the shaft ends should be enough to create these general shapes. But I'm not sure what the right workflow is. I know how to extrude flat shapes into 3d shapes from attributes, but I can't angle these away. Is there a method for connecting two xy endpoints at different z values and extruding a volume between them? ... View more

In upgrading from ArcGIS 10.4.1 to 10.5.1 I've noticed that ArcMap seems to handle raster coordinate system info a little differently now. We have an older set of 10m NED elevation rasters on our data server. In 10.4.1 these files could be re projected from their native GCS NAD 83 to any other common projected system. No errors. In 10.5.1 the same input raster will not project because Arc interprets the vertical coordinate system as "unknown" and the project raster tool hangs. If I check the reference system in the image properties in 10.4.1 I can't see any lines for the VCS. In 10.5.1 there are VCS properties for the same image and they are set to "unknown" (unknown VCS datum...). If I redefine the input raster and set the VCS on the Z coordinate system tab all works ok in 10.5.1 even if the output of project raster is set to have no VCS! The issue is, I don't understand why ArcMap suddenly cares if the VCS is set? The input file is the same in both 10.4.1 and 10.5.1. In 10.4.1 Arc seems to interpret an unknown VCS as "no VCS", in 10.5.1 it seems like I have to explicitly tell it it's no VCS or set a real VCS. What has changed about VCS handling in ArcMap at 10.5.1? ... View more

I have a student who is using the Cost Connectivity tools in ArcGIS for his research who needs to know the specific algorithm being used in the tool to determine the minimum spanning tree. The ArcGIS online help only refers to the linked wikipedia article for more detail on the method, but there are several algorithms listed there. How can he determine the specific one being used in the arcGIS tool? How the Cost Connectivity tool works—Help | ArcGIS Desktop  Minimum spanning tree - Wikipedia  ... View more

I have a student who is doing an analysis of hydraulic head along water transmission pipes in LA. He has an elevation surface and the total lines connecting various facilities across LA county. What he needs from this data are to break up the transmission lines into segments based on uniform slope. So along the path of the transmission line we'd break the line up into smaller sections based on that section having a roughly constant rise/run. We don't need segments of even elevation. A slope surface wont help as we need the slope along the direction of pipe, not in the direction of the steepest terrain. We can't just calc rise over run for his segments becasue we don't have the run part. We are basically looking for the natural breaks in elevation changes and making segments between those breaks. This seems straightforward but has been very difficult to work out. Any ideas for a workflow? - david ... View more