Category: Mapping

Copying a representation class

By Charlie Frye, Esri Chief Cartographer

Not long ago we found a workflow that demonstrated how convenient it would be to be able to copy a representation class. The situation arose as we were creating a map service for a map that had been designed for print. The problem was that many of the symbols were too small and detailed to be seen clearly on screen. Our symbols were already cartographic representations, so we didn’t want to edit them (to make them larger) because we still needed them to produce our print map. We also didn’t want to have to create and manage an extra copy of our data just to manage one additional attribute (the one added for representations). Continue reading

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Representations tip: Using data-driven settings to transition printed maps to map services

By Charlie Frye, Esri Chief Cartographer

Put yourself in the shoes of one of my interns, who was asked to use representations to replicate a 1:100,000 scale geologic map.  In less than two weeks she got it done, and did so well that the next thing I asked her to do was to test ArcGIS Server and make a map service with her map. Those intricate little point symbols on geologic maps that are rotated by their strike angles and labeled with their dip angles were just too small to be seen clearly on screen.  We needed to make them bigger.  Continue reading

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Heat map

Question: I feel silly asking this but I can’t find the way to create “heat map” style surface representations in ArcMap. Can you help?

Answer: No problem, our profession is riddled with ambiguous terminology (one of the reasons I have a job).  The Spatial Analyst has a suite of interpolation tools, and the online help for this area is generally quite good.  The intro. help topic is called Understanding interpolation analysis and the related topics will get you to the rest of what you need to know.

From your follow up email, it sounds like you’ve got  point data which will be the input to any of the interpolation tools.  Read about the various methods and determine which tool is best for your needs.  You can either set an analysis mask or use the Raster Clip tool after the fact to trim the edges of your raster output to your geography (if needed–the values outside of your geography will become NO DATA).

From there it is just a matter of choosing a color ramp to represent that values in your raster output.  See the Hot Spot Analysis map on mapping center (panel #4) for an example of this process.

Attachment: Heat Map example
Formerly a Mapping Center Ask a Cartographer  Q & A.
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Strategy question: What is the best way to manage overflow annotation on street maps?

By Charlie Frye, Esri Chief Cartographer

We got one of those perennial ‘tough nut’ questions on Ask a Cartographer today. The question has to do with using annotation versus on the fly labeling with Maplex and what are often called overflow labels, which I have also heard called “key lists”. While we are able to recommend tips and tools for specific circumstances or implementations, the person asking was more interested in what is the best strategy and why. So here’s their question: Continue reading

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Migrating Illustrator files (.ai) to ArcGIS

By Charlie Frye, Esri Chief Cartographer

Last month I was lucky enough to be invited to the USGS’s Digital Mapping Techniques (DMT) conference. Unless you do geologic mapping this conference is likely not on your radar, but suffice to say it worth the effort to get to Moscow, Idaho on many counts.  One is that I met Andrew Wunderlich, who gave a great and detailed presentation on how he has been migrating a base of Adobe Illustrator files to ArcGIS.  This question has appeared on Ask a Cartographer a number of times, where we’ve given a rather general answer.  Andrew got into the details, I know more than a few of your are faced with this task, so here is a link to the Powerpoint from Andrew’s presentation.  Andrew is also working on some additional notes and we will let you know via the comments on this posting when those are available.

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Expressing slope

By Aileen Buckley, Mapping Center Lead

The vertical change in the elevation of the land surface, when determined over a given horizontal distance-along a road or stream, for instance-is known as its slope (figure 1). There are three primary ways to quantitatively express the slope between two points. In each, the lower the slope value, the flatter the terrain, and the higher the slope value, the steeper the terrain. The slope values may be expressed as a ratio, as a percentage or as an angle. Continue reading

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Simplifying polygon map layers

By Frants von Platen, Geographer and GIS Specialist, Geological Survey of Denmark and Greenland

I have recently “invented” a method for simplifying polygon map layers, which seems to give reasonable results. Probably many others have invented it before me, but I would like to present it in order to receive comments and advice on setting the appropriate parameters.

My task was to produce a national soil map suitable at 1:1,000,000 scale on the basis of a 1:200,000 map. The best method would probably be to have a geologist or soil scientist make a complete re-production for the new scale – but we needed a less expensive method. The challenge was to find a technique that would not totally erase soil types represented as many small plygons covering more than half of the area in some regions. A traditional Generalize or Eliminate would have this result.

Continue reading

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Symbolizing a tree canopy

By Charlie Frye, Esri Chief Cartographer

Not too long ago we received a question on Ask a Cartographer about symbolizing polygons with a scalloped edge (like the old ArcInfo hardwire line symbol). Hoping to do better (scallop lines were a nice idea, but they didn’t always turn out as good as I would have liked, so I rarely used them), I started experimenting with the options in representation symbology. I’m happy to report that there is a better solution. Continue reading

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"Angeles River, Los"

By Charlie Frye, Esri Chief Cartographer

Making maps with data that were never intended for mapping has it’s challenges. One of them is trying to use the names from Geographic Names Information System (GNIS), a product of the U.S. Board on Geographic Names (BGN).  Even when someone has gone to the effort of assigning these names to GIS features, the way the names are formatted can create problems.  In the case of the GNIS, the names were formatted for an old-style (i.e., pre-modern search engine) alphabetical index that you could visually scan like a gazetteer in an atlas.  The result is that there are entries like “Great Salt Lake, The” or “Grande, Rio” which need reformatting in order to look correct on a map.  Continue reading

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Spring conference presentations

By Aileen Buckley, Mapping Center Lead

This spring, we have caught up with many of you at a number of conferences.  The presentations we gave at the conferences are now posted on the Other Resources page here on Mapping Center. Here’s a rundown of our latest activities… In April, we attended the Association of American Geographers meeting in Boston. There we gave a presentation on “Web Delivery of Cartographic Concepts and Best Practices”. Then we saw some of you at Carto 2008, jointly sponsored by the Canadian Cartographic Association and the Association of Canadian Map Libraries and Archives. At this meeting, held in Vancouver, BC, we presented an updated version of our “Evolution or Devolution of Cartographic Education” presentation and “Teaching Map Design using Mapping Center”. Most recently we attended Digital Mapping Techniques ’08 in Moscow, Idaho. There we gave a presentation on “Esri Cartographic Representations for the FGDC Digital Cartographic Standard for Geologic Map Symbolization”.

We really enjoy meeting with you at these events, and we look forward to seeing you at the UCGIS and other meetings in the near future!

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