The Geocortex Essentials team recently implemented a variety of new ways our users can highlight and store features in the map using the Geocortex Viewer for HTML5.
This addition was designed to give you even more choices, control, and flexibility to ensure you’re maximizing the information contained within your spatial selections in as simple a way as possible.
In this week’s Geocortex Tech Tip, we wanted to provide you with some orientation on all the different ways you can select features from your database.
“Hi, I’m Drew Millen. In this tech tip, we’re going to take a look at selecting features. We’ve recently introduced in a new way that users can select features on the map in the Geocortex Viewer for HTML5, so that adds to a variety of ways you can do that, and we wanted to take a look to show you how it’s done!
In this tech tip, we’re going to talk about feature selection, but it’s important to get some terminology straight before we start.
One of the ways that we can capture data off of the map, is using our Identify tool.
Identifying is the act of drawing a shape on the map and returning a set of results into either our results list or our results table. To choose which layers I want to identify, I can click on this context menu item to choose the identifiable layers. Right now, all my layers are identifiable; it’s going to return a lot of results that I’m not interested in, so I’ll clear those results and turn on my Building Footprints. Let’s assume that I’m really interested in building footprints right now.
The default identify shape that I selected, allows me to click or drag a rectangle to go ahead and return some results.
Here, we have 61 building footprints that have been returned from that rectangle that I returned.
Now, this is the results list. Another way of displaying results is the tabular view or what we call the results table and notice that the title of both the results list in the results table is showing that we’re looking at Identify Results. Because that simply an identify operation that I ran.
We can modify our Identify Results by adding results to it. If I enable this context menu item and go ahead and drag around some more parcels, part of me building footprints – they are added to my Identify Results. I can continue to do that, building up my collection. I can also subtract results if I’m not interested in the buildings in the center area.
The nature of Identify Results in the Geocortex Viewer for HTML 5 is that their transient, meaning they can easily be overridden. Let’s say, if at this point, I was happy with my results and I did a search. Notice that my search, searches from layers across the entire map because search is enabled across a number of different layers, and my buildings that I selected earlier are replaced by this new collection of 34 results across a number of different layers.
Each one of these collections; these search results or identified results as transient. Selection comes in when we want to wait to persist these results, so that we can do some further analysis.
Let’s go back to using identify tool on some buildings.
Let’s say that this is the curated selection that I wanted to make. From the context menu of the layer, I can click this link to save this list of results and I can give it a name.
Now that I’ve got a collection, I can safely close that, replace that collection and then restored it anytime.
We added a button on the toolbar to show my collections and I can also click to open any saved results.
Notice that my Collection 1, which I created here, is currently open. If I wanted to create another collection, let’s say a set of building footprints over here, I can go through the same set of actions. Save these results as Collection 2.
Now, I’ve got two collections that I can navigate between them. If I want to see Collection 1, I can look at that. I can also open my saved results and restore Collection 2. These are persistent within my session.
Alright, now that I have more than one collection, I can also do selection operations.
For example, if I want to combine the results of both of those collections into one master collection, I can click to combine those results and I’ve got a few different ways of combining them. I can simply sum them up or have a combined set of all of the results. I could subtract, meaning remove a set of results from the current list that I’m looking at, or I can only match the intersecting results and store that is a new collection.
In this case, I’ll combine both of these sets together, adding 24 features to 33, in a new collection of 57 features that I can now save as a Collection 3, for example. These are some intricate ways of working with selections of features.
In the latest release of the Geocortex Viewer for HTML5, we also wanted to provide an even simpler way of storing feature selections.
Let’s start again. Remove those selections, go ahead and identify some features on the map.
Again, this is our transient collection of features. I’ll go ahead and put it into the list view.
You’ll notice that beside each feature, we added a little star. By clicking on that, I’m persistently selecting that feature into a default selection called the “Starred Selection”. It’s kind of like another name selection just like those ones we were working with a second ago.
Now, the default behavior for any viewer that you’ve upgraded to the latest version, will behave such that, when you make a start selection, those highlights are not persistent. But, if you want to, you can make sure that your highlights are persisted and there’s a couple of good reasons for doing so.
First, let me show you how to change that behavior.
In the configuration file behind the viewer, there’s a “SelectionStar” module and there’s a “persistHighlights” setting that you can change from false to true.
I’ll go ahead and save that change and then let’s reload our application.
Now that the new configuration is in place, when I select features using that star selection, those features are going to be persistently highlighted.
Let’s open up our Identify Tools and let’s give us a couple of identifiable layers this time, building footprints and add parcels. I’ll go ahead and select features from both of those layers and switch to our table view, we don’t need our toolbar anymore.
Right now, we’re looking at a building footprints. Let’s select a couple of those and noticed now that they’re going to be persistently highlighted, so when I switch to the Tax Parcels tab, we’re still highlighting the building footprints that I selected. A good reason for doing this is if I wanted also to select the underlying parcels behind those. Now I know which building footprints are selected, I can select the corresponding parcels behind them.
I’m not going to bother trying to find them right now, I’ll just go ahead and select a few at random. And then even if I close these results all together, the yellow features are showing that they are currently activated tab and the blue features are showing those that are starred or in my starred selection.
If I close my results all together, I still persist the highlights from my parcels and buildings that are starred in my starred selection.
That’s a quick orientation to the different ways of selecting features from your database in the Geocortex Viewer for HTML 5.
Thanks for watching!”
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