Tag: overlay

GeometryEngine part 3: Overlay analysis

Click the image to open sample

This is the final post in a three-part series exploring the client-side GeometryEngine in the ArcGIS API for JavaScript. This series covers the following topics: Part 1: Testing spatial relationships and editing Part 2: Measurement Part 3: Overlay Analysis In the … Continue reading

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MapmyIndia content now available in ArcGIS online basemaps

2MMI_RoadNetwork

We recently updated our basemaps for all of India. Users will now be able to better leverage the data provided by MapmyIndia for the Indian geography through the ArcGIS platform. From scales ~1:288k to ~1:4k nationwide and at ~1:2k and … Continue reading

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More adventures in overlay: point in polygon

Households and Districts

Counting the number of points in a polygon is a  common overlay operation. But unless you’re aware of what happens when points fall on polygon boundaries, or when points fall just outside the coverage of your polygons, you may not … Continue reading

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Updated World Basemaps for Australia and New Zealand

01Perth

By Andrew Green, Basemap Project Manager From Middle Earth to the middle of the Outback, the basemaps for New Zealand and Australia have been updated on ArcGIS.com. Both countries offer a plethora of geographic and geologic wonders stretching from Australia’s … Continue reading

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Are you sure Intersect is the right tool for the job?

Are you sure Intersect is the right tool for the job?

UPDATE

ArcGIS Pro 1.0 introduced a PairwiseIntersect tool which emulates the pairwise tool discussed in this blog post.
ArcGIS Pro 1.1 has an additional pairwise tool, Pairwise Dissolve.
By default, starting in ArcGIS Pro 1.1, both the PairwiseIntersect and PairwiseDissolve tools run in parallel mode. This will allow these tools to distribute the work to all (or a portion of) the logical cores on the machine. The performance benefit of parallel processing varies from tool to tool and depends on the input data being processed.

Please see the following for more info: PairwiseIntersect and PairwiseDissolve

(Note: There are no system Pairwise tools provided in 10.x. Continue to use the provided methodology and scripts included with this post.)

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I often talk with people using ArcGIS Geoprocessing who find themselves surprised about the amount of time the Intersect tool takes to run, or confused about the output results.  Much of the time this confusion comes from a misperception about what tool to use for the analysis, or from a lack of understanding of what the Intersect tool does.

Here’s an example… A user contacted me about the Intersect tool because the tool would run for hours and then fail. They perceived their data as small and really thought Intersect would only take a few minutes.

My first question, and one you should ask too is, “What do you really want for a result?”

The answer in this, and many cases was “I want to know how much of each feature in input 1 is in each feature in input 2.”

Cool!  That means Intersect is not the right tool to use! Continue reading

Posted in Analysis & Geoprocessing, Python | Tagged , , , , | 31 Comments

More adventures in overlay: Spatial Join and the Field Map

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In my last blog post I showed how you could resolve 1:M relationships found in overlapping polygons using the spaghetti and meatballs technique. The model described in that post used used the sample  Concatenate Row Values  tool available from the … Continue reading

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More adventures in overlay: spaghetti, meatballs, and the one-to-many problem

Stacked 1:M labels

In my last blog post, I showed how you could count the number of overlapping polygons using the spaghetti and meatballs technique.  In this post, I want to go a little further and show how you can use this technique … Continue reading

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More adventures in overlay: counting overlapping polygons with spaghetti and meatballs

Spaghetti And Meatballs

In my last blog post about overlay, I introduced the concept of cartographic spaghetti and how it can be used to split polygons by line features. In this post, I want to continue with the cartographic spaghetti theme by introducing … Continue reading

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More adventures in overlay: splitting polygons with cartographic spaghetti

OverviewMap_1

In my previous blog post about overlay, I showed how to create simple tabulation tables using a variety of geoprocessing tools.  In this post, I continue with the theme of overlay by introducing an overlay methodology that can be useful … Continue reading

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More adventures in overlay: comparing commonly used overlay tools

In the blog about distributing data and analysis, I showed using the Tabulate Intersection tool to overlay archeological sites and land parcels to create a table containing information about each parcel within an archeological site. Figure 1 shows the data and the results of Tabulate Intersection. This “what sites overlay what parcels?” question is a classic overlay query. These types of queries are the bread-and-butter of geographic analysis.
Continue reading

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