Latest Contributions by DavidMedeiros

‎09-27-2013

I have an ArcMap mxd with a dozen or so layers that I want to publish to ArcGIS online as individual feature services (rather than publishing the entire mxd as a feature service). What is the fastest way to move these layers to my ArcGIS online account so they can be used in a Web Map? It seems like options for uploading are: Create a Layer package that publishes online, but this seems to only create a downloadable version of the layer, not one that can be added to a web map. Export each layer to .shp, but this requires separate zip folders for each layer (not a big deal but not super convenient). Create a separate mxd for each layer (also not very convenient). Or??? Ideally, I'd like to keep the symbology I set in ArcGIS when uploading these layers, but that doesn't seem to be possible. I'll probably export to zipped .shp files but was hoping there might be another option. Thanks, David

‎09-19-2013

Unfortunately, it is not possible to copy layers you'd have to add them again via their URL to My Content. You can copy a web map by doing a "save as" when editing the web map. This copy will be independent of the original, although will reference the same layers. Thanks, Mike So am I right in thinking that by adding them via the URL to my new sub folder in my content, that this is not an independent file but a reference back to the original file location. If the original file changes or is deleted my "copy" will be changed as well?

‎09-12-2013

I'm taking over an existing ArcGIS Online project and rather than work directly in the current map services and data layers I want to copy a set to a new folder in my account so I don't disrupt the old set as I play around. How can I copy select features and tiles I have in one folder (Branner Home) to another (Campus Base Map)? I see that I can Move the layers over, but I'm concerned this will disrupt the current Web Map that calls those layers. I can use Add Item in the new folder but that doesn't create a copy of the layer, it creates a "Map Image" (??) of the layer. I'm assuming this just means it points back to the original layer and if anything happens to it, my Map Image will be affected. Is it not possible to simply clone the layer and add to a new folder in ArcGIS Online?

‎08-19-2013

What version of ArcMap your are using? Across versions the NoData handling has changed with ESRI and I suspect it might have something to do with that. Before doing Geo-referencing confirm the pixel depth and then after doing it. Try with a high no data value and see if it resolves the problem I've been meaning to update this. The issue was resolved, sort of. It turned out that our original images were not 16 bit as previously thought, they were only 8 bit. ArcGIS, on rectifying, converted them to 16 bit as a result of the no data value being set to 256 by default. This added an extra color, or an alpha channel, not sure. the result was the image bumped up to 16bit and was also unreadable in PS (although I still don't know why, PS can read 16 bt images). Converting back to 8 but fixes the issue as does manually setting the no pixel value to 0. I would have assumed Arc to be smart enough to set the defaults based on the input data set, but hey. Recommendations from others in the field who are doing this same type of work has been to work in a GIS package that handles raster formats better than ArcGIS does, like Global Mapper.

‎08-14-2013

We are geo referencing a series of scanned historical maps. The map scans are 16 bit tif images which open ok in Photo Shop before referencing. Once geo refed and rectified the images look ok in ArcMAP but appear all black in PS despite still being 16bit tifs. The only fix we have found so far is to convert in Arc to an 8 bit tif or jpeg via Raster to New Format. This is ok for general use but we still need original full 16 bit tifs as our master files since some of our users will want the highest resolution an color depth possible fro these maps. Can anyone tell me why the image shows up ok in Arc but not in PS and how I can get these to display in PS as geo refed 16 bit tifs?

‎06-23-2013

Looking for some best practices for using ArcScan. I'm running a workshop on ArcScan but I'm having a very hard time getting AS to work with the demo image I have (http://bluebook.state.or.us/images/state/legislative/maps/bb_SD_map1000.gif). I have the extension turned on, the image converted into a 2 color image using symbology > classified, and I'm in an editing session. Most of the tools are active but using the Vectorization Trace tools don't work. I keep getting an error about the snapping environment settings. I've played with all of the settings that I can find references to in the ArcScan help but no change. I've also tried to run my image using the Automatic Vectorization tutorial but can't get the erase or delete selected cells functions to work. Very frustrating. The ESRI help on this disjointed, info on settings and options are spread over a large number of related pages. Any help on figuring out what I might be missing would be greatly appreciated! David

‎06-05-2013

As I'm working through this I'm beginning to realize why this won't work. How can you have a distance value in a pixel that is different distances away from multiple upstream sources? You could do it stream segment by segment. Or from the bottom of the network, but not the top I guess. This is for a student I'm helping here and I think I'm at the point where I need to know more about what question he's trying to answer with this before proceeding. Stream Order or Network Analyst may have be substituted. I'm still curious though, as this has come up before. When thinking about a cost path analysis and modelling river networks into that, how can you model directionality? Flow? So that the cost model takes into account the benefit from traveling down stream if that's allowed by your model, but the added cost of traveling up stream?

‎06-05-2013

Yes, the tool is in Spatial Analyst and called Flow Length: http://resources.arcgis.com/en/help/main/10.1/index.html#//009z00000053000000 Thanks, unfortunately as with all of these tools they rely on creating a river network (or a flow direction surface) from the DEM. I was looking to calculate these distances along an existing river network that has been rasterized. I tried faking it by buffering my streams and extracting the DEM values inside the buffer as the input to the Flow Direction tool. But the results are irregular. I think Flow Direction needs a large surface to run on. I'm trying again with larger buffers, or extracting the buffer area of the full Flow Direction raster. Will report back.

‎06-05-2013

Is there a way to generate a pixel by pixel distance accumulation of a raster river network, where the distances accumulate along the river pixels from headwaters to outlet? This would be similar to running Euclidean or Path Distance tools except only on the river pixels, and with distance increasing along the river network, not away from it. The ultimate goal would be to create a set of rasters for the river network: 1)distance along the network 2)upstream travel cost 3)down stream travel cost.

‎05-22-2013

Can any one here comment on the use of Clip (Raster) or Extract by Mask for clipping portions of a mosaic in to a new raster? My reading of the help suggests these shoudl work on a mosaic data set but I always seem to have issue with them. I just ran an extract by mask using a polygon on and ASTER DEM mosaic and although it completed ok in just a few minutes the resulting DEM was a checker board pattern, not a DEM raster.

‎05-10-2013

If all the points in your 'point stack' have a common ID (i.e., "STACK_ID"), try using the Summary Statistics tool. You'll find the MAX of the DEPTH field and your Case Field is your STACK_ID. The result will be a table that will have a record for each unique STACK_ID with the maximum depth. What it won't have is the alkalinity field value for that point. But you do have enough information (the STACK_ID and the DEPTH) to find that unique point using an attribute query. The way I'd do this is to create a new field on the point feature class that concatenates STACK_ID and DEPTH. This would be a text field. See this blog post on how to concatenate field values. If you can create this field on your point feature class, you can also create it on the output of Summary Statistics. Then you have a common key field to use in joins and relates. You could use Join Field to join alkalinity from the point features to the statistics table for example. If you have an advanced license, you could use the Sort tool to sort your points on STACK_ID and DEPTH (descending) , then use Summary Statistics with the FIRST statistic to find the alkalinity value. STACK_ID would be your Case field. This'll return the first value of alkalinity found for each unique STACK_ID. Since the table is sorted, the first occurrence is the deepest point. There's probably a better way to do this using an SQL query, but I can't think of it right now. I think that will work. I already have the unique ID for each stack (concatenated X and Y coordinates) so that as the Case Field in the summary statistics tool should give me what I need to join back to the data to get the max points. I'll try it with the student I'm helping when we meet next week and will report back if this was the solution. Thanks!

‎05-09-2013

I have a "grid" (vector grid) of evenly spaced points for ocean alkalinity. At every location in the grid there is a stack of up to 15 points with identical coordinates but different values for their depth and alkalinity attributes. I need to join the alkalinity values for the deepest points at each location to another point layer. How can I create a selection that will grab just the deepest points at each location? This is not a simple get max value from the entire layer problem, I need the points with the max depth value at each of 6000 point stacks. I've tried various versions of this: "depth" = (SELECT MAX("depth") FROM INPUT) in the select by attribute window but get a bunch of syntax errors. I'm pretty sure I also need some other selection attribute like a unique coordinate ID so I'm picking the max from each stack and not just the whole data set. I have that ID created. Any help is greatly appreciated! David

‎05-02-2013

That was it, thank you! I assumed the network consisted of all the objects participating in the network analysis. No I just need to go back and tweak some of the settings but this works!

‎05-01-2013

I have a single point file of hospital locations in CA, and the ESRI major roads layer for CA. I need to calculate the distance in miles between each hospital and every other hospital in the point file. I have added both the points and the roads to a simple network data set. I created an OD cost matrix and added the input points as both the Origins and the Destinations and tried to solve. The result is one short 'line' for each input point, basically single distance of zero miles since the tool seems to only be reading the nearest origin and destination pair. How do I setup the OD cost matrix to give me distances between all of my points along the road network? Thanks, David

‎04-29-2013

Ok, that's very good information, thanks. I guess I shouldn't be too surprised to find that Arc uses more than one method of geometric computation depending on the tool specified. The output coordinate system environment setting is one I've never used before so that's helpful. Too bad it does not apply universally across all tools and processes. At any rate, I know have solid information for explaining how Arc works with projections in its computations. Thanks again, David

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My Ideas

Latest Contributions by DavidMedeiros

Best method for uploading multiple layers individualy to ArcGIS Online?

Re: Copy layers to a new folder in My Content?

Copy layers to a new folder in My Content?

Re: Rectified 16 bit tif appears black in PhotoShop?

Rectified 16 bit tif appears black in PhotoShop?

ArcScan settings and best practices?

Re: distance and cost raster, along river network?

Re: distance and cost raster, along river network?

distance and cost raster, along river network?

Re: Best methods for extracting or clipping from mosaic data set?

Re: select max value per feature location for overlapping point features

select max value per feature location for overlapping point features

Re: dist. along rds for each point to all other points in single layer (OD cost matri

dist. along rds for each point to all other points in single layer (OD cost matrix)

Re: Projections effect on GIS computations? Area and distance measurements in the GIS

Allow admins to reset orphaned offline use license...

Re: Rectified 16 bit tif appears black in PhotoSho...

Collect GPS locations by angle and distance offset...

Can you copy symbology from one Feature Layer to a...

Add an Extent parameter to Disperse Markers tool