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[Last Updated February 23, 2019] In a previous post, we explored how expressions in the calculation column of your XLSForm could be used to programmatically set values on a geopoint question. In this occasion, we will do the opposite. That is, we will describe how you can extract data out of a geopoint. Here are some good reasons why you may want to do this: Store geopoint properties as attributes: Often times, keeping the X/Y coordinates of a point encoded in a geometry field is not ideal.  By pulling data out of a geopoint question you can store the X/Y coordinates in specific fields. You can also extract and store other values from your geopoint properties such as the elevation, speed or horizontal accuracy if present. Having all these values as attributes can help during QA/QC as well as data exchange processes.  Storing metadata about your locations is particularly important if you are  using an external GNSS receiver with Survey123, because all that metadata is critical to understand the quality of your data. Build data validation rules: You can use geopoint properties in your form to create data validation rules in your form. For example, you can create a rule to warn users if a particular horizontal accuracy has not been reached, or if the location has been captured while the field user was traveling at an excessive speed. What a geopoint is made of? We all know that geopoint questions store location information, but what is really inside a geopoint value? At a minimum, unless a geopoint question is empty, you will always find the latitude and longitude of a location. Survey123 never works with projected coordinates: geopoint values are always in geographic coordinates using WGS84.  Now, you could potentially find much more than just a latitude/longitude pair within a geopoint value. The most common properties include: Property Name Description Units x Longitude, positive in eastern hemisphere, negative in western hemisphere Decimal degrees y Latitude, positive in northern hemisphere, negative in southern hemisphere Decimal degrees z Altitude, meters above sea level Meters horizontalAccuracy Horizontal accuracy of the x and y coordinates Meters verticalAccuracy Vertical accuracy of the z coordinate Meters speed Ground speed Meters per second verticalSpeed Vertical speed Meters per second direction Direction of travel measured clockwise from north Decimal degrees magneticVariation Angle between magnetic and true north Decimal degrees positionSourceType Returns the category of the position source.  Unknown (0), User (1), System Location (2), External Device (3), and Network Device (4). fixType Returns the type of position fix the coordinate has. Potential results are NoFix (0), GPS (1), DifferentialGPS (2), PrecisePositioningService (3), RTKFixed (4), RTKFloat (5), Estimated (6), Manual (7), Simulator (8), and SBAS (9). If a geopoint question contains all the properties above or a subset, depends on the following: If the location is set by the end user by manually tapping on the map, then only the x an y properties will be populated. It is possible to also let the user type the elevation, which ultimately would populate the z property.  If the location is set by the device, the number of properties with data will depend on the device and also on how that location was obtained.  The accuracy of the values found in each property is as well completely dependent on the device providing the location information to Survey123. If relying on consumer devices to retrieve the location properties above, you should take values with a grain of salt. Your average iPad or Android smartphone could often give you a reasonable x,y and horizontal accuracy but everything else could or could not be trustworthy. In fact, many consumer devices do not even populate most of the properties above. I do not want to say consumer devices will give you useless geopoint  properties, but you should proceed with caution understanding through trial and error what devices and in what conditions will give you accurate information.  By connecting Survey123 to an external GNSS receiver, not only you can significantly improve the location accuracy of your data, but also get many more properties associated with your geopoint values.  Here is a list of the most important properties you can get. The complete list is available in our help. Property Name Description positionSourceInfo.deviceName The name of your external GNSS device positionSourceInfo.deviceType Indicates how your GNSS is connected to your device.  Unknown (-1), Bluetooth (0), Serial Port (1), and Bluetooth LE (2). positionSourceInfo.antennaHeight The user defined GNSS antenna height. positionSourceInfo.altitudeType Indicates the selected altitude type: altitude above mean sea level (0) and height above ellipsoid (1). geoidSeparation Returns the difference between the WGS-84 earth ellipsoid and mean sea level as reported by the GNSS receiver. This is also sometimes referred to as orthometric height. accuracyType RMS (0) and DOP (1) positionAccuracy Returns the mean radial spherical error. Encompasses both horizontal and vertical error. differentialAge Returns the age of the differential signal and correction used by the GNSS receiver to differentially correct the position. referenceStationId Returns the differential reference station ID (DSID) of the station used by the GPS receiver. satellitesVisible Returns the number of satellites visible at the time of location capture. satellitesInUse Returns the number satellites being used to return the position data. Reading geopoint properties using the pulldata function All the geopoint properties described above can be extracted using the pulldata function. For example: pulldata("@geopoint", ${location}, "horizontalAccuracy") The "@geopoint" parameter  to the pulldata function indicates that values will be extracted from a geopoint value. The second parameter indicates the question in your XLSForm that holds the actual geopoint value. You will want to make sure that the question you reference is actually of type geopoint. The third and last parameter defines the geopoint property you want to extract. You will want to make sure the property name is included in the table above and make sure that you specify it with the proper capitalization: HorizontalAccuracy is not the same as horizontalAccuracy. Learning by Example: Here is a simple XLSForm that will extract the X,Y and horizontal accuracy of your geopoint and store these values as attributes. Using this technique, you have complete freedom as to which fields in your feature service will be  used to store the geopoint properties.  You use the Name column in the XLSForm to define which field will keep the data. Type Name Label Calculation geopoint location Location decimal Latitude Latitude pulldata("@geopoint", ${location},"y") decimal Longitude Longitude pulldata("@geopoint", ${location},"x") decimal HorAccMeters Accuracy pulldata("@geopoint", ${location},"horizontalAccuracy") Realistically, I would never store geopoint properties as illustrated in the example above. Mostly because I would not want end-users to get distracted with questions in the survey that get automatically populated with these properties. I would not want end-users to modify these calculated values either.  A more  refined approach would be to set  the Type of question as hidden. In this way, the Latitude, Longitude and accuracy questions will not be shown in the form, but their information would still be sent to the feature service on submit. To ensure  the actual values are stored as numbers in the feature service, I would also set the esriFieldType column to esriFieldTypeDouble as shown here: Type Name Label Calculation bind::esri:fieldType geopoint location Location hidden Latitude Latitude pulldata("@geopoint", ${location},"y") esriFieldTypeDouble hidden Longitude Longitude pulldata("@geopoint", ${location},"x") esriFieldTypeDouble hidden HorAccMeters Accuracy pulldata("@geopoint", ${location},"horizontalAccuracy") esriFieldTypeDouble When working with horizontal accuracy, you should also learn about the meaning of the accuracyThreshold column. You can use very similar expressions in your constraints and relevant statements. In the next example, we will pop a message in case that the geopoint value was captured while moving faster than 0.2 meters per second. Type Name Label Relevant geopoint location Location calculate speed Speed pulldata("@geopoint", ${location},"speed") note Do not move while fixing location! 0.2<number(${speed}) Like every time you use pulldata() it is best practice to use this function alone. This is why I broke down my last example into two separate questions: One calculate question to invoke pulldata() and a separate question where I compare the output of the pulldata function with a number. In this blog post I simply wanted to introduce the use of the pulldata("@geopoint") function. With it, you can build expressions to persist location metadata as GIS attributes, but also to create powerful data validation rules in your smart forms. ... View more

This blog introduces Trek2There, a new mobile app from Esri Labs just published to the Google Play and iTunes app stores. You can think of this app as a smart compass that will always point to your destination.  Unlike an ordinary compass, always pointing to magnetic North, this app will use your direction of travel to tell you in what direction you should go to reach your destination. Best of all: you can integrate this app with Survey123! Esri Labs projects are developed by Esri employees and are inspired by our interactions with ArcGIS users like you. Esri Labs projects are free to use but are not official Esri products. These projects do not go through the rigorous software development cycle so they are not holistically tested, documented or supported by Esri technical support. Trek2There is particularly helpful when you are trying to find a location in an area where you cannot get driving directions. If you are working for example in a forest, or in a large agricultural property with not even dirt roads, using straight-line-navigation is often the most practical approach to arrive to a known location.    Trek2There only requires two things to work: First, the destination where you want to go provided in geographic coordinates (Latitude/Longitude). Second, it requires you to be outside and moving so your device can fix your location and determine your direction of travel. Let’s first try the app and then I will explain details of how to make it work with Survey123.   Trek2There, a quick first test Start by downloading Trek2There onto your Android or iOS device.  First, you need to feed the app with the coordinates of your destination, which can you can enter manually or alternatively pass from a separate application. For now, we will use a simple web-based app to pass the coordinates. On your device, launch this web app and tap on the map to select your destination. Next you will see a new dialog open from which you can launch Trek2There.   Now that the app is running, start walking in any direction and shortly the arrow will rotate to show you the direction and distance to your destination.  Walking with caution and avoiding physical obstacles is all on you!  As Trek2There is launched in your mobile device, please be aware that the arrow and distance will only calibrate correctly when you start moving (walk, drive etc). You need to be outside and moving before Trek2There will give you any meaningful information.  Trek2There uses your direction of travel to determine the direction in which you need to go. If you stand still, the arrow may temporarily point away from your destination, but things will go back to normal once you start moving again.   Trek2There custom URL scheme Using the app is straight-forward as you can see. Launching it and passing the coordinates of your destination is what takes some thought but do not worry, it is not complicated at all. Trek2There can be launched remotely by invoking its custom URL scheme: arcgis-trek2there://?stop=38.133453,-117.223455 If you copy the above string and paste it into a browser on your device, you will be able to launch Trek2There and set its destination at the provided latitude and longitude. You could send this URL as a link in an email, or programmatically invoke this URL from a custom developed application.   Launching native apps like Trek2There through a custom URL scheme -also often referred to as a deep-link- works fairly well across all platforms when you invoke the URL from a custom native application.  If you invoke the app from a web browser it will work as expected on Windows, iOS and Mac. On Android you may find issues launching the URL scheme from some mail clients and in the Chrome browser.   Working with Trek2There and Survey123 for ArcGIS You can integrate Survey123 and Trek2There via the custom URL scheme described above. As you may already know, Survey123 forms can include a small subset of HTML. HTML formatting is used to make your questions look better, to organize notes etc  HTML can also be used to include links in your surveys and as you can now imagine... HTML links can launch Trek2There. The trick is to dynamically create these links, so you can control the coordinates passed to Trek2There. To illustrate this concept Survey123 Connect includes the Trek2There Test sample survey.  This survey includes a choice list with all Esri offices worldwide.Using the pulldata function and a calculation, an HTML link is created dynamically so the coordinates of the Esri office in the selected country are passed into Trek2There. The actual list of offices may be out of date, but you get the idea... You may want to use a similar technique to add your own assets for example. To open the Trek2There survey sample, install Survey123 Connect for ArcGIS in your desktop. Then click on New Survey and look for the Trek2There survey under the Samples category.  In the XLSForm you will see that a calculation is used to get the coordinates of the selected asset and dynamically generate a HTML link rendered in a note.   First, the pulldata function is used to lookup from a CSV file the latitude and longitude of the selected element in the list. The CSV file is called EsriDistributors.csv and can be found in the media folder of the survey. To learn about pulling data from CSV files  in Survey123,  I recommend you look at this help topic. pulldata('EsriDistributors','Lat','Country',${Country}) Both values are persisted in calculate questions so we can reuse them later on. Then these coordinates are used to generate an HTML link using a calculation in a note question.  concat('<a href="arcgis-trek2there://?stop=',${Lat},',',${Lon},'">Launch Smart Compass</a>') Following the pattern illustrated above, you can now use your own lists of assets and integrate Trek2There  into your own surveys. Since Trek2There is only available for Android and iOS, keep in mind that you will not be able to test the integration unless you download the survey into your phone or tablet. . Invoking Trek2There programmatically In a web app or website, simply create an HTML link: <a href='arcgis-trek2there://?stop=38.133453,-117.223455'>Launch Trek2There</a> In QML AppStudio for ArcGIS: Qt.openUrlExternally('arcgis-trek2there://?stop=38.133453,-117.223455') In Java, using Android's Intent: PackageManager manager = mContext.getPackageManager(); Intent i = manager.getLaunchIntentForPackage("com.esri.survey123"); i.setData(Uri.parse("arcgis-trek2there://?stop=38.133453,-117.223455")); startActivity(i); . Customizing and Contributing to Trek2There The source code of Trek2There is shared under the Apache 2.0 License, so if you like you can take this app and make it your own. Perhaps you may want to embed this functionality within your own app, or re-brand Trek2There… your choice! You can find the source code at https://github.com/Esri/Trek2There.  Esri welcomes contributions from anyone and everyone. If something is not working for you, create an issue... if you actually know how to fix existing problems or want to contribute, please follow these contributor guidelines. You may wonder, how this app was built. Just like Survey123, Trek2There was developed using AppStudio for ArcGIS.  AppStudio for ArcGIS is quite a powerful product for building your own cross-platform native GIS apps. If you are a Javascript developer, transitioning into AppStudio for ArcGIS is relatively easy. If you like tinkering with Python code in ArcGIS, becoming an AppStudio for ArcGIS efficient developer is perfectly within reach.  With AppStudio you write your code once, and then you can easily compile your work so it runs on desktops (Windows, Mac, Ubuntu Linux) as well as tablets and phones (iOS, Android, Windows). The easiest way to download the source code is by using AppStudio for ArcGIS Desktop Edition.  Once installed, click on New App and search for Trek2There under the Enterprise category.  You can look at the code, modify it and run it in your Mac or Windows development machine. If you have an AppStudio for ArcGIS Standard license, then you will be able to compile your code for Windows, Mac, iOS, Android and Ubuntu Linux. The AppStudio for ArcGIS GeoNet Group is quite active. A great place to address technical questions. You see, even if Trek2There is not an app you ever use, if may be worth looking into its source code to get familiar  with AppStudio. After all, just like Trek2There, the source code of the Survey123 field app is also available with AppStudio for ArcGIS. Can you imagine adding your own features into Survey123? Hmmm, that may be a good idea for a separate blog post. ... View more