Latest Contributions by ChrisDonohue__GISP

Wait, Sephe, are you sure about that?  You do work with GIS, after all...  Chris Donohue, GISP ... View more

Sephe - I think it was deleted.  I just re-read the thread and it is gone. Chris Donohue, GISP ... View more

Some things to be aware of: Most AutoCAD files do not employ a Projected Coordinate system.  Instead, they are set up with a local non-Projected coordinate system, typically with the lower left corner being 0,0.  So as a result they will not align with any Projected Coordinate system. AutoCAD does not normally provide for projections unless one gets added components like Autodesk Civil 3D (which is not that commonly used), so the resulting files, even if set up in the same coordinate system as desired, will be off from projected data as it is not projected (i.e. most CAD files are "flat-world"). As a result, the data almost always has to be adjusted.  Typically this is done by Georeferencing. A quick tour of working with CAD data ArcGIS Help (10.2, 10.2.1, and 10.2.2) Chris Donohue, GISP ... View more

Not sure about the Mouse locked to zoom issue - maybe the computer needs to be rebooted? In regards to Georeferencing your image, some advice, assuming you are using ArcMap: Georeferencing is not intuitive in many ways.  For example, one can't really drag an image around to help align it.  Instead, one gets it "somewhat close" with the "Fit to Display". To align the image, one creates control points by finding common information on both images and drawing the links.  This involves zooming back and forth, from the image you want to georeference to the known data.  Once you have several good control point links, you can do the adjustment. The actual adjustment of the image is not done by selecting it in the Table of Contents (which would be intuitive).  Instead, in the Georeferencing Toolbar, the image to be georeferenced needs to be chosen in the pulldown on the left. As Sephe mentioned, this is not a straightforward process to do the first time around.  I think all of us who have learned it pulled out our hair a bit at first, as it is easy to get tripped up.  If you know someone in your organization who could show you the ropes on it, that would help tremendously.  Georefencing is one of those easy things to do once you know it, but the initial learning curve is steep, as there are many things which can trip one up. One tip for something I learned the hard way - Don't use a Map Rotation on your Data Frame at all.  It is tempting to rotate the data frame to make viewing the data easier, but this will deactivate the Georeferencing capabilities.  So if you have the Data Frame Toolbar up, be sure the Rotation is set to zero the entire time you are Georeferencing - don't change it.  Even if this means georeferencing an image that is upside-down.... Fundamentals of Georeferencing ArcGIS Help (10.2, 10.2.1, and 10.2.2) Chris Donohue, GISP ... View more

As an addition to what Wes suggests, another idea is to create the symbology for all the types, make multiple copies of this, then remove all the types from each copy but the one you want displayed.  Then repeat for each single item you want displayed, so you end up with multiple "layers" of the same data each only showing one item, which gives you flexibility on displaying the data. Not an elegant approach (Definition Queries are preferred), but workable if all you want to do is easily display data without having to figure out queries. To do so: In the Table of Contents area in ArcMap, right-click on the layer you want to symbolize. Choose "Properties..." from the list that shows up. Click on the "Symbology" tab. On the left, under "Show:", click on "Categories" and then select "Unique Values" (or "Unique Values, many fields" if that is more appropriate to your data). In the "Value Field" box, click on the pulldown and choose the field in your table that provides the differentiation. Choose a "Color Ramp" that looks good for your data. Hit OK.  Now, to copy the symbolized layer, right-click on it in the Table of Contents and choose "Copy" In the Table of Contents, right-click on the word "Layers" and choose "Paste Layer(s)".  Repeat as needed. To reduce the categories showing in a symbolized layer, first repeat steps 1-3 to get back into the symbology tab. Then right-click on the symbology that you don't want displayed and choose "Remove Value(s)" (or highlight it and click the "Remove" button). Under "Symbol", uncheck the checkbox by "<all other values". Hit OK when done.  Now one can use the checkboxes next to each symbolized layer to turn each layer on and off as desired. Caveat:  This method only works for visual display of the data.  It does not limit the data in the table; the data table for each layer still has all the data. So if you want to know how many of a type you have, you will need to take additional steps to determine that. Chris Donohue, GISP ... View more

Yes, you just hit "Add data" and choose your tiff. But before doing so, be sure there are a few things you want to set up: Add to ArcMap the data that you will be using to align your tiff to.  Be sure to do this BEFORE adding your tiff. The reason to add it before is that ArcMap will default to the coordinate system of the first layer added; your tiff has no coordinate system. Once you get the reference data in, check to see what the coordinate system is. In ArcMap, Table of Contents area, right-click on Layers. Choose "Properties" from the list. Click on the "Coordinate System" tab. Check to see what coordinate system was chosen.  Be sure it is a "Projected Coordinate System" (scroll up to see what heading the system is under).  If it is a "Geographic Coordinate System", you will need to decide on an appropriate Projected Coordinate System (which is a much larger discussion than can be explained at this juncture). Chris Donohue, GISP ... View more

I confirm what Darren said - Maplex used to be a separate, but now it comes with all versions of ArcGIS.  I'm tempted to say the change happened at version 10.1, but I could be wrong. The biggest challenge with Maplex now is remembering to turn the darn thing on for each of your data frames (the default is "Standard Label Engine").  Chris Donohue, GISP ... View more

Some practical tidbits to add regarding using Public Land Survey System (PLSS) data: You may notice parts of the PLSS "grid" to be missing.  This is because not all areas were surveyed. In some areas, the "grid" becomes distorted and linework expected to be parallel converge to some extent.  Instead of a uniform grid of repeating rectangles, there are other geometric forms.  This is due to inaccuracies of the surveying.  Note the offset and "bent" lines in this example from Northern California: Also, here's some history and explanation of common terms used in the survey. Public Land Survey System - Wikipedia, the free encyclopedia ... View more

If you can get the polygon data into a Parcel Fabric, there may be a way to do this with the Parcel Editor Tools.  Here's some information to get started: ArcGIS Help (10.2, 10.2.1, and 10.2.2) ArcGIS Help (10.2, 10.2.1, and 10.2.2) Chris Donohue, GISP ... View more

So if I understand your dilemma correctly, the issue is the overlapping polygons (circles) not being processed correctly by the Zonal Statistics tool.  If that is the case, the help for the tool offers this explanation and resolution for this issue: If the zone feature input has overlapping polygons, the zonal analysis will not be performed for each individual polygon. Since the feature input is converted to a raster, each location can only have one value. An alternative method is to process the zonal statistics iteratively for each of the polygon zones and collate the results. Source:  ArcGIS Help 10.1 So the solution then would involve iterating the Zonal Statistics tool for each individual polygon.  Common ways to accomplish this include Python and Modelbuilder (using an Iterator). Chris Donohue, GISP (EDIT:  fixed typos] ... View more

If you do want new polygons created from any overlaps, one approach would be to use the Union tool.  This will create new polygons from the overlapping extents while maintaining the polygons that don't overlap.  Note that overlapping polygons will have the attributes of all the inputs. Union (Analysis) ArcGIS Help 10.1 Chris Donohue, GISP ... View more

In response to your question: I do not know if I'm right, but if a polygon have an overlap with another polygon, the merge function creates a new internal polygon to these two areas. So, if shape of the United States has an overlap with the Canada, the merge function will create a new polygon, as if there were another country that does not exist. Is that right? Merge will not create a new polygon where there is an overlap.  It will overlap the polygons. ArcGIS Help 10.1 Chris Donohue, GISP ... View more

I'll second that.  I've found CAD2Shape to be very useful in converting CAD.  Of the several workflows available to convert CAD, CAD2Shape has been the most effective for me. Chris Donohue, GISP ... View more

In regards to the mouse, note that being able to depress the mouse scroll wheel is not intuitive (whereas rolling it is).  I had a mouse with this capability for several weeks before realizing it would depress besides scroll. Also, be sure if you get a mouse with a scroll wheel that it does have the depress capability, as not all come with this functionality. Chris Donohue, GISP ... View more

I feel your pain.  Lately I have been cleaning up landbase layers with thousands of small slivers and gaps where judgement calls need to be made for many, so can't programmatically fixed them all in one shot by geoproccessing.  So lots of viewing of small polygons.  Quite tedious. I'll mention this in case you haven't discovered it yet.  If you are using the Error Inspector (Topology toolbar), use the handy shortcut of "Z" to zoom to the selected issue in your Error Inspector results.  You may still have to zoom in more, but it saves some effort when moving from one issue to the next. Also, if you don't have one, a mouse  with a scroll wheel can be of great help.  Rotating the scroll wheel handles  the zoom in/out.  Depressing the scroll wheel allows panning. Chris Donohue, GISP ... View more