Diverging Color Ramp addin for ArcMap 10.4

In my previous post about the Combined Field Statistics addin for ArcMap I mentioned that it was inspired from another addin toolkit I am currently developing which analyzes and displays rates of disease occurrence in a map.  In this post I want to share with you another addin project which was borne out of the disease mapping project.  This one is called Diverging Color Ramp.  This addin enables you to intelligently apply a dichromatic color ramp to feature layers containing points, lines, or polygons in ArcMap 10.4 and above. It is somewhat similar in capability to the smart mapping tools in ArcGIS Online and is useful if you need to display data with values that diverge from a specific threshold value which you define.  The screenshot at the top of this post shows a map layer of population density where the colors diverge from an arbitrarily defined threshold value of 40,000/square mile.   Other examples of threshold values might include 1.0 for ratios, 0.0 for values which represent gain or loss from an average value, or any value which represents a significant threshold of interest in your data.

This tool gives you a great deal of control over how a feature layer is rendered.  It provides a pair of default color ramps, one for for values above the threshold and another for values below the threshold, as well as a separate threshold color symbol.  If you don’t like the colors you can change them to anything you like by accessing them from the Style Manager in ArcMap.  You can also choose the classification method and number of classes, and even choose the number classes which are generated for values above and below the threshold.  This addin also has a “secret” trick up it’s sleeve.  When it generates the symbols for each class in the map layer’s renderer, it actually makes a clone of the symbol for the first class in the current renderer to use as a template for the rest of the symbols.  After that is simply sets the background color of each symbols  to colors pulled from the color ramps.  This makes it easy to quickly apply global changes to other properties in the symbols, such as outline color or fill pattern, since you only have to make the change in the first symbol and then apply it as a template to each of the symbol classes with a single button click.  This is a fun tool to use since it makes it easy to try out different ways to visualize your data.  I hope you enjoy using it.

Download links:

Diverging Color Ramp (addin + documentation)

Diverging Color Ramp (source code + documentation)

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Combined Field Statistics Addin for ArcMap 10.4

I’m currently working on a new add-in toolkit for ArcMap 10.4 to analyze and display rates of disease occurrence in a map.  This is a work-in-progress and I will provide more details about it in the coming months.  But in the meantime I want to share with you the result of a smaller project that was borne out of the disease mapping project.

One of the requirements for the disease mapping project is the ability to calculate the sums of values from age group columns in a feature layer.  Generally, the tool of choice for a task like this is the Summary Statistics geoprocessing tool in ArcToolBox.  However, I also needed the ability to calculate sums from the combined values in multiple age group columns.  For example, to calculate the total number of individuals in columns for ages 0 -4 and 5 – 9, to obtain an aggregate total for ages 0 – 9.

It occurred to me that this capability could have broader applications if the tool could also calculate the full set of statistics provided by the Summary Statistics tool.  So I decided to build a more generic stand-alone addin tool in parallel with the disease mapping toolkit.  The result of this effort is the Combined Field Statistics Addin.  This tool is very simple to use and includes a detailed user guide to get you started.  It also generates an output log so you can keep track of how the tool was configured to generate a particular output.  If this capability sounds useful to you give it a try and let me know what you think in the comments!

Download links:

Combined Field Statistics (addin + documentation)

Combined Field Statistics (source code + documentation)

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Dimension Explorer version 1.11 for ArcMap 10.4 plus Source Code

The source code for Dimension Explorer, an add-in for exploring time-aware and multidimensional data, is now available for download.  Version 1.11 is a minor update from version 1.1 and is built specifically for ArcMap 10.4.  This version features tighter integration with the ArcMap Table of Contents window – as layers are added, removed or changed, the  contents of the layer selection list in the Settings window are updated accordingly.

Update – I’ve had reports that the layer selection list is not getting updated consistently as layers are added, removed, or had their properties updated in the map document.  Until this issue is resolved, I recommend users of ArcMap 10.3.1 and 10.4 use version 1.1 of Dimension Explorer instead.  I apologize for any inconvenience this may have caused.

Download links:

Dimension Explorer 1.11 (addin and documentation)

Dimension Explorer 1.11 (source code and documentation)

Dimension Explorer 1.1 (original blog post)

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Creating Fences and Curtains with Geostatistics

The parallel fences generated in the X and Y directions by two separate runs of the Parallel Fences tool.

This article introduces and discusses a geoprocessing toolbox that can perform geostatistics on vertical slices of three dimensional point clouds.

Click here to download the toolbox.

For years the users of ArcGIS and its Geostatistical Analyst extension have been able to perform sophisticated geostatistical interpolation of the data samples in two dimensions. With that, the creation of continuous maps of any phenomenon that was measured only at selected locations was feasible. With the growing popularity of analysis in 3D and the availability of 3D data, the necessity of an option to perform geostatistics on 3D data is in demand. Studies of atmospheric cross-sections, geologic profiles, and bathymetric transects became an integral part of GIS. In each one of these three classical elements (air, earth and water), we can measure natural phenomena, such as the gradient of air temperature, the content of an ore at various depth of the geologic strata, or the salinity of the ocean along adjacent vertical transect lines.

In GIS we analyze not only the natural phenomena, but also those that are man-made. Human impacts on air, earth, and water are also measured. Among those human contributions to the environment that could be analyzed in 3D are plumes of air pollution and oil spills. The later may migrate down in the ground and be moved by the ground water drift, or migrate from the bottom of an ocean up to its surface while sometimes being dragged by ocean currents. Having an insight into such occurrences can greatly increase our understanding of the phenomena. This was the motivation for creating the 3DFences Toolbox.

A slice is a vertical subset of the 3D data analogous to a slice of bread from a loaf. While typically narrow in one dimension it still is a 3D object. A fence is a 2D representation of a slice of 3D data. All points which belong to a slice are projected, or pressed onto a 2D plane. The term of a fence diagram, or a fence, is used in geology to illustrate a cross section of geologic strata generated from an interpolation of the data coming from a linear array of vertical drillings. The equivalent of a fence in the atmospheric sciences is usually referred to as a curtain.

Top view of a slice of points shown in purple, and the resulting fence presented as a colored line in the center of the input points.

Side view of the input slice points located on one side of the resulting fence. The points are the measurements of oil in sea water after an oil spill.

To be explicit, the tools in the 3D Fences toolbox do not perform 3D interpolation. The approach offered by the 3DFences Toolbox does not implement geostatistical analysis directly on the vertical slices of the 3D data. Instead, the tools transform a slice of the 3D data, with its X, Y, Z, and the measure of a phenomenon component by rotating it by 90° to a horizontal 2D plane. The geostatistical interpolation method of Empirical Bayesian Kriging (EBK) is performed on these points producing either the geostatistical surface of Prediction, which is a continuous map of the concentration or intensity of something, or a map of the Prediction Standard Error, which can be explained as a map of a degree of confidence in the Prediction map at each location of the map. The resulting output is converted to a point dataset where the points represent the interpolated value at the center of the raster cells. The points are then placed back into the original coordinate space as a regular matrix of points resembling a fence. The fence is positioned in the center of the selected points of the initial slice, when displayed in ArcScene or ArcGIS Pro. The raster is converted to a point dataset because ArcGIS does not currently support display of raster data as a vertical plane and point symbology options provide added flexibility in displaying results.

Any of the ArcGIS standard or geostatistical point interpolation tools could have been implemented in the tools. For the prototype, we have chosen the Empirical Bayesian Kriging (EBK) geostatistical method known for its best fitting default parameters and accurate predictions.

The 3DFences toolbox consists of three separate tools to support different methods of generating fences. The Parallel Fences tool can generate sets of parallel fences in the directions that are related to either longitudes, latitudes or depths.  In other words, the output sets of parallel fences stretch from N to S, W to E, or through the Z dimension.  The number of these fences in each set is determined by the user. All of the tools support selection sets to create fences from a subset of sample point features.

A fence created along digitized “S” shape.

The Interactive Fences tool can generate fences based on lines digitized on the map. The user sets the buffer distance from the digitized line. All points that are located within the buffer will be used for the geostatistical analysis. The user may digitize multiple lines and even self-intersecting lines with many vertices. The third tool, called Feature based Fences, creates fences based on existing features in a polyline feature. In this case the fence shape is determined by the existing feature(s) and extends through the Z dimension of the selected sample points. As an example, it might be applied to investigate for oil leaks above an oil pipeline placed on the sea floor.

All of the tools contain options enabling the user to determine the minimum number of sample points and fence size required to generate a reasonable geostatistical surface. The tools are also time aware. If the sample data contains a date-time field and the option is enabled, a fence will be generated for each time interval if the samples for that interval and location meet the minimum requirements set by the user. The resulting fences representing consecutive time windows are positioned at the same locations. Thus, to enable better visual analysis, these should be displayed as time animations.

An example of an atmospheric curtain created from backscatter data acquired by NASA from its Calipso satellite orbiting at 32 km above the Earth’s surface.

Contributed by Bob G. and Witold F.

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Dimension Explorer 1.1

A new version of Dimension Explorer is now available for download.  Dimension Explorer 1.1 is an addin tool for exploring time-aware and multidimensional map data in ArcMap 10.3 and above.

Here is what’s new in version 1.1:

  • map layers created with the Make NetCDF Raster Layer and Make NetCDF Feature Layer geoprocessing tools are now supported.
  • map layers with vertical dimension values defined as ranges (e.g. 0-10 meters, 5-50 meters, etc) are now supported.
  • export a map animation in ArcMap to a series of still images to create video animations with applications such as Windows Movie Maker and ffmpeg.
  • various bug fixes and optimizations.

Here is a video animation of the minimum Arctic sea ice extent for the years 1979 – 2014.  I created it with Windows Movie Maker using still images exported via Dimension Explorer 1.1.  The map includes a time-aware layer created with the Make NetCDF Feature Layer geoprocessing tool with data from the NOAA.

Dimension Explorer 1.1 can be downloaded here

If you are looking for data to get started with Dimension Explorer,  the NOAA Earth System Research Laboratory, Physical Sciences Division, (NOAA/ESRL PSD) has many large collections of spatial scientific data for climate and oceans in NetCDF format.  I recommend starting with their gridded climate datasets.   You can add most of their datasets to ArcMap using the Make NetCDF Raster Layer geoprocessing tool.  If you get the error “One or both dimensions have variable spacing in their coordinates”, use the Make NetCDF Feature Layer geoprocessing tool instead.  If the datasets are stored as multiple files representing the data at different times, use the Mosaic Dataset to temporally aggregate the files using the NetCDF Raster Type.  Finally, if you are working with temporal data of any type, be sure to time-enable the layer in ArcMap.

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Poles of Inaccessibility

Ürümqi in China is the remotest location on Earth, geographically speaking of course. This discovery and the analysis behind it are discussed in a recently published story map entitled Poles of Inaccessibility.

Vilhjalmur Stefansson, an Icelandic explorer, introduced the world to the concept of inaccessibility with his 1920′s computation of the Arctic’s pole of inaccessible. Story map authors Dr Witold Frączek and Mr Lenny Kneller recomputed this Arctic location and inaccessible locations in six continents. Frączek and Kneller computed and compared remote locations using geodesic and planar computations. Differences were small with the exception of the Eurasian continent which has a variation of approximately 11 kilometers.

The authors discovered that South America was essentially bi-polar with respect to inaccessibility. While both locations are located in Brazil, and separated by 1,400 km, the difference in inaccessibility was less than a kilometer. It is conceivable that the order of remoteness may change with the interpolation and generalization of the coastline.

Lastly, I would encourage you to take a moment to read and view Frączek and Kneller’s Poles of Inaccessibility.

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Dimension Explorer

Update - a more recent version of Dimension Explorer is now available.  Click here for more information.

Dimension Explorer, an addin tool for ArcMap, has just been released by the Esri Applications Prototype Lab!

Dimension Explorer 1.0 makes it easier to work with  time-aware and multidimensional data in ArcMap 10.3 by providing slider controls for navigation.  It works by retrieving dimensional information from a map layer to build an interactive dimensional model that can be edited and saved in the map document.  Dimension Explorer is the successor to the Timeliner addin for ArcMap, which also works in ArcMap 10.3 and can be downloaded here.

Click here to download Dimension Explorer

With the 10.3 release of ArcGIS, the mosaic dataset now supports multidimensional data in NetCDF, GRIB, and HDF format.  Dimension Explorer supports map layers based on mosaic datasets and image services which are time-aware or multidimensional, and time-aware feature classes.

Download Dimension Explorer and let us know what you think of it in the comments!

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Hydro Hierarchy

Hydro Hierarchy is an experimental web application for visualizing the US river network.

Click here to view the live application.

Source code is available on agol and github.

There are approximately a quarter of a million rivers in the United States, but only 2,500 are displayed in this application.  This subset represents streams with a Strahler stream order classification of four or greater.  The stream data used by this application is derived from the USGS‘s National Hydrographic Dataset and has undergone significant spatial editing.  Streams geometries have been adjusted to ensure connectivity, generalized for small scale mapping and re-oriented in the direction of flow.

River flow data was acquired from the USGS’s WaterWatch website.  Each river segment is attributed with the average flow for each month in 2014 and the ten year monthly average.  Computed values, in cubic feet per second, represent the flow at the downstream end of each river.  Flow data is displayed as a column chart on the left hand side of the browser window whenever the user’s mouse passes over a stream.

The preview animated image at the beginning of this post may look sped up.  It is not.  Upstream and downstream rivers are highlighted in real time as the user moves his or her cursor over the hydrologic network.  This performance is achieved using connectivity information loaded when the application first starts from this file.  The file was creating in ArcMap from a network dataset that included the river feature class.  Using this script, connectivity information for each network node was extracted and arranged into a hierarchical data structure.

The radial and column charts on the left hand side of the application are generated using the D3 graphics library.  The column chart displays 2014 flow data for any river segment that is directly below the user’s mouse.  The horizontal red line represents the ten year mean monthly flow.  Note that for most river segments, only one or two months ever exceeded the ten year average.  This is indicative of 2014′s drought, at least with respect to river flows over the past decade.

Contributed by Richie C. and Witold F.

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Solar Eclipse Finder

Solar Eclipse Finder is a JavaScript-based web application that displays past and future solar eclipses that pass through a user defined location.  The source data is published as an AGOL hosted service with the paths of 905 solar eclipses from 1601 to 2200.  The eclipse paths were prepared by Michael Zeiler from data courtesy of Xavier Jubier.

The live application is available here.

Source code is available on agol and github.

Originally developed 2½ years ago as a Silverlight-based web application (see blog posting here), we wanted to confirm that the same performance and advanced symbology is achievable today with HTML5/JavaScript in modern browsers.

jQuery & Bootstrap

jQuery is a JavaScript framework for DOM manipulating.  It is important to note that jQuery is not a prerequisite for mapping apps using Esri‘s ArcGIS API for JavaScipt. It is however a prerequisite of many third party JavaScript libraries like Bootstrap, a popular user interface framework.  This application uses Bootstap’s popover tooltips in the fly-out attribute window and its modal dialog during start-up.


The tapered symbol used by eclipse shadow paths is achieved using a linear gradient fill.  Linear gradient fills are not supported by ArcGIS API for JavaScript.  However linear gradient fills are supported by SVG, the underlying technology used by Esri’s JavaScript API for renderering vectors.  We used Mike Bostock‘s D3.js JavaScript library to insert and apply linear gradient fills directly to the map’s embedded SVG node.


Updating this application was a two step process.  First the eclipse dataset was republished as an AGOL hosted feature service and, second, the app was rewritten in HTML/JS.  Both tasks were relatively effortless and only took a couple of days in total.

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GeoJigsaw is a community driven geographic jigsaw puzzle.  If you are feeling creative you can create a puzzle and share it with the puzzle community.  If you are feeling competitive, try beating the high score on someone else’s puzzle.

Click here to view the live application.
(works best in Microsoft Internet Explorer and Mozilla Firefox)

Click here to download the source code from ArcGIS Online.  A simpler version of this application is available on github here.

GeoJigsaw is a JavaScript-based web application inspired by a Silverlight application developed about two years ago called Puzzle Map.  Unlike a recently published geogame that uses Facebook, in this application we wanted to explore anonymous collaboration.  That is, anyone can anonymously create, share and play puzzles.


In the app developed two years ago, the puzzle design was static.  In this application we wanted to offer puzzles of varying difficulty and size so we needed to implement a technique of dynamic puzzle creation.  After a little research we discovered this example of a voronoi tessellation using D3.  D3′s voronoi implementation and associated SVG-based visualization library are the basis of this game.

Unlike the D3 sample, our app did not use completely randomized points.  If a user created or selected an “impossible” puzzle then a 10 by 10 grid of points is created and nudged slightly before being turned into 100 piece voronoi diagram using D3.  This was only part of the puzzle (excuse the pun), each piece needed the addition of one or more tabs.  Tab addition is essential to give the game its recognizable jigsaw look. Through a process of iteration, tabs are appended to any side of sufficient length and reversed if an opposing tab exists.

SVG Filters

The finishing touch to give the puzzle a realistic look is the application of an inner bevel using a SVG filter.  SVG filters are hardware accelerated in Internet Explorer and Mozilla Firefox but not in Google Chrome.  Unfortunately the Chrome’s software rendering of SVG filters makes complex puzzles almost unplayable.  This may change in future releases of Chrome.


Puzzles designs, ratings and scores are stored in ArcGIS Online (AGOL) hosted services.  We intended the application and associated services to be accessed by non-AGOL users.  This meant that AGOL user credentials could not be used to restrict access to prevent unanticipated malicious activity.  As such, we used the security model discussed in the previous post, that is, app registration and an intermediate web proxy.

Libraries Used


This project demonstrations that modern browsers are more than capable of impressive visualizations without the need of plugins such as Silverlight or Flex.  We also wanted to experiment with anonymous game play, time will tell if the lack of user identification is an incentive or disincentive to play.  Good luck!

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