February 2018 update for the latest workflow:
With the availability of receivers like Trimble’s R2 that can be used for high-accuracy data collection in 3rd party apps, we all want to know, “How can I achieve vertical accuracy using Esri’s Collector App?”. Hopefully, this will become easier over the next year with improvements coming in Collector and ArcGIS Pro. But for now, you have to do a little work.
There are a lot of variables to consider, including your receiver, your correction source, your horizontal datum, etc. Each setup may be different, and we’re here to help if you need it. But let’s take one example and maybe you can take it from there. Let’s say I’m using an RTK R2 receiver capable of 1 cm accuracy horizontally and 2 cm vertically. I will be connected to a local VRS so that I can achieve centimeter level accuracy in real-time. The VRS outputs corrections in a NAD83 (2011) datum. My local data is in a standard, boring (but nice and safe) Latitude/Longitude, WGS84 coordinate system. I would like my final vertical results to be in Mean Sea Level (MSL) using the NAVD88 vertical datum. There’s a lot going on there, so let’s start unpacking this.
Set Up the Attributes
As of today, Collector does not record 3D geometry. You will start with a 2D (non-Z-enabled) feature class. The way to get that vertical component starts with adding the Altitude metadata field to your feature class. Vertical accuracy will be achieved in the field by Collector in real-time, but the Z value will only be recorded in the attribute table… for now.
Set Up the Collector App
Collector is an easy-to-use data collection app, and most people can be up and running very quickly without much training. However, if you are looking to achieve high accuracy, or better yet high vertical accuracy, you will need to pay close attention to your settings.
Now comes the fun part. You’re back in the office with your collected data, and you are ready to turn your 2D feature class into a highly accurate 3D feature class. First we will use the Recreate Geometry tool that was included with the tools we downloaded in step one.
Reproject to NAVD88
Time to finally get these vertical coordinates into Mean Sea Level in feet which is what I really wanted to begin with. Previously, you had to do only one reproject at a time, but now you can reproject both horizontal and vertical together eliminating some of the previous steps.
Convert to Feet
Yes… that was a lot of steps. If you can eliminate any steps and get the same results, I want to hear from you!
But this could be easily automated right? Drag all those tools into a model and off you go. Or better yet, build a Python script that automatically downloads the new data from ArcGIS Online, runs all these processing steps and then merges with your existing data. Have it run overnight, and you’ll never have to look at it again!
… okay well, at least until the next update…
Need some help? We can automate all these processes and customize it to your system, so don’t hesitate to get in touch!