Latest Contributions by DavidMedeiros

‎10-19-2016

Darren, that's it, thanks. I knew it would be something simple. I don't usually work with imagery other than as source for vectorization so never pay much attention to color settings. If I want a high quality background, typically do that outside of Arc. This will help the team a lot as they need to produce a near seamless appearance for this mosaic for use online. Cheers, David

‎10-19-2016

I have a team working on digitizing a set of historic OS maps of London in ArcMap. The source maps are coming from two different locations, one is a large mosaic of OS tiles in JP2 format from the David Rumsey collection (see link below). The other images are individual .tif files filling in a few holes in the larger set. When opened in an image viewer the tif images and the jp2 image have a similar natural or "creamy" color to them. But when placed in ArcMAP the tif images become washed out and grainy. They look more straight black and white and are quite harsh compared to the jp2. In the top image below the outer area is the jp2 with the tif placed over in the center. Below that is the exact same tif opened in an image viewer. You can see the very noticeable difference in rendering quality. What is causing this? How can I preserve the appearance of the original image when importing to Arc? FYI, both the jp2 and the tif are 8 bit unsigned integer images (the jp2 is 4 band, the tif is 3). Composite: London 753 Sheets. - David Rumsey Historical Map Collection

‎09-03-2015

That seems like a hassle. Why wouldn't the Web App also auto generate a thumbnail or take it from the Web Map it was created from?

‎05-14-2015

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

‎05-13-2015

That's what I'm finding. Enabling Z values in the environment doesn't seem to effect the out put of a Data > Export Data flow that won't help quickly create a Z aware copy of the data. Maybe I can hunt down a tool that will use that environment setting. Like I described above, it's easy enough to re import points from a table and add the Z awareness then, but what would a user do who receives an existing 2d line for say trails in a park and then ants to use some of the 3d tools that require a Z aware line layer. Would they have extract the nodes, export an xy table, re import with Z values, the re connect the nodes into lines? Seems absurd.

‎05-13-2015

To help clarify the question. I'm not looking for ways to visualize or represent the data in 3d, but to make the properties of the data change from not having Z values to having Z values. If you check the properties of any GIS data layer you will see an indication of the presence or absence of Z values for that data. For point data for instance I know that you can make them Z aware while creating them from a table of XY coordinates. But for existent GIS data, is there a way to make them Z aware after the fact?

‎05-13-2015

Many (all?) 3d tools only work with Z aware feature layers. Is there a way to take an existing point, line, or polygon data layer that has no Z values and make it a Z aware layer without having to re import the points or digitize the the lines or polygons into a new layer?

‎02-19-2015

Step one of almost any research project here is to get out of GCS, unless the interpolation that causes changes the raster values we need to evaluate. With data like LandScan global pop rasters you don't want interpolate the pop values before measuring them, the same might be true of the night lights data but I think the variation is probably minimal at the admin 2 level. My stats background is limited so I wasn't aware that you could derive the percentile from the mean and standard deviation. I doubt the data are going to be normally distributed though, it's likely to be a skewed distribution for many parts of the world with far more dark pixels than very bright. I'll have the researcher sample a few zones to be sure. Apart from that I take it there is no simple method for tackling this question? Even breaking the raster up by admin 2 zones before vectorizing seems daunting.

‎02-18-2015

I'm helping a researcher who is evaluating the pixel statistics of Night Light data by admin zone. She wants to calculate (along with normal zonal stats) the 5th and 95th percentile values for pixels in the raster by zone. Given a raster with an attribute table, this would seem easy enough to accomplish but I can't figure out how to do this without tackling a conversion of the raster to points to allow for a spatial join between pixel values and admin ids before exporting to a table. Not practical for a global raster dataset. Any help is appreciated. David

‎12-17-2014

I have a 3d density surface representing water sample data taken along a stream network. I would like to visualize this as spikes just along the stream bed. Is there a way to take the surface I have and trim it to some linear feature (like a 10 or 20 meter river buffer), so the spikes remain but the edges are clipped or trimmed at the edge of the buffer? I tired extracting the surface by the buffer and setting the base height to the extraction and that results in a ribbon of pixels at the Z value higher but there is no fill to the bottom of the surface (like an extrusion).

‎12-11-2014

Thanks Mike, That looks to be relevant only to the Enterprise Login function, which I don't have set up at the moment. I inherited management of our account and need to investigate the Enterprise function at some point. That said, I would think this would be a general Roles function and available universally across AGO instead of just under Enterprise. David

‎12-10-2014

Thanks Heath, I thought I'd read or heard that AGO admins were able to set the default role to a custom role. I assumed this meant there was a AGO admin feature to change the default role as opposed to needing to script something. Too bad, seems like a simple and obvious add on to AGO control for Esri.

‎12-05-2014

I have the same question. How can I verify (and then change) the default role? I've created a custom user role with limited credit spending abilities that I'd like to be the first role applied to each new account, rather then having to change the roles manually.

‎10-23-2014

That was my assumption, but the hazy area is that inside Pro there are geoprocessing tools for Spatial Analysis and Network Analysis as well other tools for things like Info Graphics that cost credits within AGO. I would assume that these run locally in Pro and do not consume credits, but with Pro requiring an AGO log in, I can't take the risk that there are hidden paths to credit usage in the tool my users need to know about. Is any of this spelled out in the Pro documentation? Is there any warning on tools or processes inside Pro that would let you know you are about to use a credit based service in the app (if that's possible)?

‎10-22-2014

How do you envision the user experience should be? Intuitive. I always start with a search as well, but usually look for the specific forum or topic I'm interested in first. GeoNet is designed from the discussion level down instead of the topic level. It's vaguely social media based and I get the desire to incorporate that feeling here, but it should be easier to start a topic focused question as well. I'm sure people are getting used to it, I find it disorienting when it differs so much form almost every other support forum I've ever used. I have the same complaint about ArcGIS Pro BTW (unintuitive documentation and user interface). For an app that requires an AGO log-in to use, answering the question of credit usage should have been in the FAQ ; )

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Date Last Visited	‎11-26-2023 07:39 PM

My Ideas

Latest Contributions by DavidMedeiros

Re: ArcMAP images washed out

ArcMAP images washed out

Re: Thumbnails for Web Applications

Line segments from uniform slope along a path?

Re: How can I make an exisitng 2d polyline layer Z aware?

Re: How can I make an exisitng 2d polyline layer Z aware?

How can I make an exisitng 2d polyline layer Z aware?

Re: Raster value percentiles by zone?

Raster value percentiles by zone?

Trim 3d surface by line or poly features?

Re: Enterprise login and roles

Re: Enterprise login and roles

Re: Enterprise login and roles

Re: Does ArcGIS Pro consume AGO service credits?

Re: Does ArcGIS Pro consume AGO service credits?

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

Re: Thumbnails for Web Applications