Top 5 reasons why I made the switch to ArcGIS Pro (3 of 5)
November 2, 2016
by Robert Krisher
Senior Consultant at POWER Engineers
This article was originally published as a LinkedIn Article
Reason #3: Scale Ranges
In the first two articles of this series I focused on the inherent benefits of switching to ArcGIS Pro. In the remainder of the articles I want to focus on new configurations and architectures introduced with ArcGIS Pro. By using these new features you should be able to improve end-user experience, reduce the amount of effort it takes to maintain your GIS, while simultaneously improving performance across the board. If it sounds too good to be true I challenge you to try it out for yourself and let me know what you think, you won’t be disappointed. With those lofty statements out of the way I want to spend the remainder of this article examining how ArcGIS Pro improves upon one of the most foundational GIS activities – building map documents.
If you follow the steps I’ve outlined in this article, you should be able to quickly reduce the number of layers in your map document, improve draw times in your map, and all without compromising the look and feel of your application! If you want to review the first and second articles, see the earlier posts below.
ArcMap Scale Suppression
For those of you who are familiar with building map documents, you’re likely well versed in the art of “less is more.” One of the most common problems we tackle is trying to find the right scale for our data. While it’s relatively easy to determine how far zoomed in you can get on the data, determining how far users should be able to pan out is much trickier. You need to balance the desire to see data when zoomed out with poor draw times and clutter often associated with large data sets. We can often manage this by classifying the features in our data set and allowing the application to only draw certain classes of features at different scales. In the case of a utility, this may take the form of different voltage levels, pressure classes, or something like a backbone/trunk/mainline indicator. In the case of transportation data, this may take the form of alleys, streets, and highways and we would typically manage this by only showing interstates and highways when viewing the whole state, but as we drill down into a county or city level we will want to start seeing all of the smaller roads.
Using ArcMap you would need to control this sort of behavior through the use of scale suppression and definition queries. A definition query allows you to apply a filter to a layer such that only a certain set of rows are displayed on the map. Scale suppression on a layer allows you to define the zoom level(s) in your map document when a given layer should be visible. Using these two techniques together, we can create a group of layers for each scale in our map document and apply scale suppression and definition queries to each of these groups of layers to have complete control over the look and feel of our map.
This technique is common practice for creating base maps or other complex map products that are held to a high cartographic standard. However, this technique presents several challenges. First, the sheer number of different layers we have to maintain drastically increases the amount of time it takes to make even the smallest change. Second, having so many layers can sometimes result in usability and performance issues if the display is used in any sort of editing or mobile application.
Using Scale Ranges
Fortunately for us with ArcGIS Pro we can use the new “Scale Range” feature in the symbology tab to consolidate these multiple layers into a single layer. This allows you to control the scales at which individual symbols in your layer turn on and turn off. For instance, you will have a single layer that shows you highways/interstates while zoomed out, but as you zoom in it will start to show freeways, major roads, and eventually all of your minor streets and alleys.
For those of you already doing this using the old ArcMap method, this new feature should let you significantly reduce the total number of layers in your map document. For those of you who haven’t been using this technique, I highly encourage you to check it out as it’s one of the quickest, cheapest, and easiest ways to reduce map clutter and improve drawing times.
Let’s walk through a quick example of this in ArcGIS Pro. First, I add a layer to a new map that contains all of my roads. Each road has been categorized as a “Primary,” “Secondary,” or “Village” road. As you can see, my map looks cluttered when I draw everything while zoomed out. If I were to start layering other data on top of this, it would be difficult to find anything and would start drawing pretty slow.
Next I open the symbology dialog and switch to the “Scale Range View.” From here we can then use the resulting slider bar to control when each symbol turns on and off.
By adjusting the slider bars we can achieve the same behavior as using multiple layers with definition queries and scale suppression. In this example, I have primary always on by leaving its slider bar alone, have secondary turned on at 1:100,000, and have village turned on at 1:50,000.
Here’s what our map now looks like when zoomed out. It’s only showing the major roads in the area and it’s very easy to see what is going on in this map.
Zooming in further we can start to see more detail and our map still looks pretty good.
Finally when we zoom into the data even further, we can then see all of the features. Even though this final scale is starting to get pretty cluttered, we are still able to make sense of the data.
One technical footnote: I want to make you aware of one drawback with this feature. While ArcGIS Pro is smart enough to only query the database for features that will be drawn, you need to update the scale suppression once you know the upper scale range for your layer. However, because labelling features is done separately from drawing features, we can have several higher-level scales where we label features without drawing them. This technique is a useful trick for labelling features – like regional offices or distribution stations when it wouldn’t be meaningful to draw them. It works great for a layer with less than a thousand features, yet it isn’t appropriate for layers that have several thousands of features at higher scales.
How much does this new technique improve performance? If I compare an optimized ArcGIS Pro display against an un-optimized ArcMap display I reduced drawing times from over 2/3 of a second down to about 1/6 of a second. By optimizing the ArcMap display, I was able to cut its drawing time in half under the worst case scenarios, but even with these improvements, it was usually drawing 20%-100% slower than ArcGIS Pro during complete screen redraws.
However, with the introduction of ArcGIS Pro you also get the ability to perform continuous panning. Because ArcMap doesn’t have this feature, I wasn’t able to compare numbers, but during my continuous panning tests I was able to pretty consistently get almost 60 frames per second! If you’re looking for tools to test out your performance for either ArcMap or ArcGIS Pro, I recommend you check out some tools provided, without support, by Esri Implementation services:
This concludes my third of five articles, and hopefully at this point you are feeling a little more confident using ArcGIS Pro. I’ll be building on that confidence and the techniques described above in my next article where I show you another feature of Scale Ranges in ArcGIS Pro that will either help the look and feel of your map document or help you consolidate even MORE layers in your map document.
About the Author:
Robert is a Senior Consultant in POWER’s Geospatial and Asset Management group with over 10 years of industry experience. Robert excels at pushing the boundaries of what is possible with GIS and related technologies at utilities, often by re-purposing proven technologies and methods in clever ways. As an active member of many early access programs across the industry and author of more than a dozen published articles, Robert is a recognized expert with Esri’s latest technology including ArcGIS Pro and the new Utility Network. He loves finding innovative solutions to complex challenges and sharing his insights with the GIS community. If you have any questions or comments for Robert, you can contact him at firstname.lastname@example.org.