Rural Water District Goes High Accuracy |Q & A

Document created by MLamas-esristaff Employee on Sep 27, 2016Last modified by MLamas-esristaff Employee on Jan 23, 2018
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This is the Q & A from the webinar, Rural Water District Goes High Accuracy

 


Q1: Was the student only collecting above ground points? How did you collect the below ground points (pipelines)?
A1: Yes, the student was only collecting above-ground points.
The only way to collect below-ground points would be to already have the utility marked by means of tracer wirer, have it exposed, or use something else like ground-penetrating radar to mark the line first.


Q2: What was the handheld device used?
A2: The first handheld that Le-ax started with was a Trimble GeoXT 2005. The second unit was a Trimble GeoXH 2008.


Q3: Can you identify the manufacturer and model of the handheld GPS unit?
A3: Eos Positioning Systems, Arrow 100 GNSS


Q4: Right now the collector app cannot go offline if you are using related tables. Is this being resolved?
A4: I can’t really answer that one. I don’t use related tables. I would reach out to the Collector Community within ESRI Online and pose that question. Someone should respond.


Q5: What external GPS unit are you using?
A5: Eos Positioning Systems, Arrow 100 GNSS


Q6: We have a GeoXH 2008 Series, will this work with Collector using any mobile device such as a Samsung phone?
A6: I don’t know how you would make that work. I don’t think you could connect a smart device to the GeoXH to use its internal GPS.


Q7: I understand using an ipad for collecting points. My question is did you check the accuracy of the data. Any chance you checked into a known GPS point like a USGS momument? If so how close was it?
A7: If you set the fields up correctly on the feature you are collecting, the Arrow 100 GNSS will pass the metadata on to Collector. You can then view that information in the attributes.
No, I did not check it with a known GPS point. Our county has 3-inch aerials that we can easily see our hydrants, and sometimes valves and meter pit lids. If the collected points show up on top of these identifiable features then I am happy with the data I’m receiving. Although, when I get time I probably will compare it to a known USGS point.


Q8: What are you considering 'high accuracy'?
A8: If we have an available network where I can connect to our RTK network, I’m considering
A sub-foot as high accuracy. Where we work, however, a data connection isn’t always available so when we use the differential correction service from the Arrow 100, we are sub-meter. We usually seem to be around 0.5 meters. The area where we work is pretty hilly, and contains a lot of forest area.

 

Q9: What about the GeoXH coupled with a Rangefinder?
A9: I have no experience with that type of setup.


Q10: Air 100?
A10: Eos Positioning Systems, Arrow 100 GNSS

Q11: Can multiple people concurrently collect data to the same map/version or does each person upload/sync to their own version?
A11: Yes, they are collecting data using the same map and data, not their own.

Q12: How do you account for offsets? (Ie: points you cannot occupy). How about the offset between the valve lid and the main if it is a butterfly valve?
A12: We personally don’t have situations that require an offset, or haven’t yet. I understand what you are asking, but I don’t think there is a way to take a point, and then offset that point 10 feet and use that as the collected feature. You certainly can take a point and then drag it to an area on the screen (if you had an aerial for reference), but it would have to be a very high resolution aerial in order to maintain some kind of accuracy.
All our valves are gate valves.


Q13: Can you collect points with collector then upload to ArcGIS desktop? Is that an easy process?
A13: When you collect with Collector, the points are automatically updated on ArcGIS Online (AGOL). You can then pull those points back down by logging into AGOL from the File menu and then click Add Data and choose Add Data from ArcGIS Online. When the window displays, click My Content and select the layer that you want to add.


Q14: What types of GPS receivers does Collector support for high-accuracy collection? (To receive the metadata.)
A14: Please use this link for reference: https://doc.arcgis.com/en/collector/ios/create-maps/gps-receiver-support.htm


Q15: Will Collector work with a GNSS receiver other than the Arrow 100?
A15: Please use this link for reference: https://doc.arcgis.com/en/collector/ios/create-maps/gps-receiver-support.htm


Q16: Can you go over what an RTK network is? How much does it cost? How to you connect to the RTK network.
A16: Real Time Kinematic (RTK) positioning provides correction to a compatible GPS receiver. Virtual Reference Station (VRS) is a system composed of hardware and software designed to facilitate real-time GPS/GNSS positioning based on a set of reference stations. Through the internet we utilize our Ohio Department of Transportation’s VRS network to provide us with this correction to our Arrow 100. This is what gets us from sub-meter down to inches.


Q17: We are unable to locate the login details for our free ArcGIS Online Organizational account that was included with our ArcGIS Desktop. Wondering if any of you could help us figure out how to recover the login?
A17: I think what you need is your ESRI Customer ID. I believe you need this in order to create your online account. If you can’t find that I would call customer support, and they should be able to help.


Q18: If we have GPSd our assets already, collector would have the capability of snapping to the feature if it is in the shp file, correct? This is for a maintenance record on an asset.
A18: Yes. You would have to upload the shapefile to AGOL first, and it would convert your file to a hosted feature layer. After you create a web map, and add that layer to it, you would then be able to select that feature and update the maintenance record. What I describe above is pretty simple to do.


Q19: Is the $2,900 cost of one GNSS receiver?
A19: Yes. For the Arrow 100 the price was around $2,900.


Q20: Did you have security concerns hosting all of your assets online?
A20: No. I sort of felt that way in the past, but I don’t now. I would say it’s more secure being hosted online by ESRI (and their partners) than it is on your office desktop. The only concern I think you would have is accidentally having someone making a map “public” instead of “private”. You can control that so it’s not much of an issue if you are the one creating the maps to be pushed out to employees.


Q21: Did you purchase/need additional ArcGIS Online licenses for your field crew?
A21: At first I did everything with our 1 free account that we received with our ArcGIS Desktop license. When we went to two GNSS receivers, I then purchased the minimum of 5 online licenses. The field crew uses two, the office staff has one, I have one, and one is issued to our maintenance program (valves and hydrants). That doesn’t mean that someone else can’t log for something else. I wouldn’t call them absolutely dedicated to these particular employees/groups.


Q22: Where did you rent the trial equipment from?
A22: The company that I used was Fondriest Environmental here in Ohio. They simply will overnight a receiver to you and give you the instructions on how to return it. They were very helpful.


Q23: Does the collected water data reside in ArcGIS SDE and/or connected to an asset management software?
A23: No, ours does not.


Q24: Did you have any issues with the integrity of your data? I.e. trusting all the different field workers collecting points? Did you get some accidental points?
A24: No, not really. Although, I’m not getting large amounts of points per day. On a normal day, I would say I might get 6 points max. I suppose you could get an accidental point, but you have to hit a “Submit” button in order for that to happen. But if it was accidental, you can simply tap that point, and delete it.


Q25: How many credits you consume for the services?
A25: I myself consume very little credits. All I have done is upload my layers and created a web map. That doesn’t consume any credits I don’t believe. Storage consumes credits, but it’s very little. I don’t think I would have consumed 100 credits for a whole year on the amount of data that I have hosted on AGOL. I haven’t really used any of AGOL’s analytics either. This is where you can consume large amounts of credits. If all you are doing is pushing layers to AGOL and creating a map, then absolutely don’t worry about credits. It’s extremely cheap.


Q26: Travis, what is your background?
A26: I’m a Mechanical Engineering graduate from Ohio University. I was a private consultant with engineering firm before coming to work at Le-Ax Water District. I’m also a licensed engineer in the State of Ohio.


Q27: How do you store your data accuracy in your geodatabase?
A27: When you set up the attribute table for a particular layer, you add specific names to each field so that the GNSS receiver passes the metadata onto Collector so it populates those fields. For example, the field name ESRIGNSS_PDOP represents the PDOP accuracy and that number is passed to Collector and populated in the attribute table.


Q28: How are you differentiating between pipes that you have dug and taking a GPS point on top of the point and pipes that the location is estimated?
A28: With our system, you could pretty much say it’s all estimated. When we grab a point that’s a pipe locate, I’ll use that point to adjust the waterline. I haven’t done this yet, but I may make a domain within the pipe layer with 2 fields; one “estimated” and one “adjusted” or something similar and use color to differentiate the two.


Q30: I would like to know if you can get Collector to work with a Trimble Geo XH 6000 or 7X
A30: I really can’t answer that question. You may want to reach out to Trimble.


Q32: Is that GNSS device precise enough for finding valves in a snow drift? Would you consider upgrading to the new Arrow 200 to get more precision in regards to valves?
A32: I would think so. I certainly would have a probe rod, and a metal detector if snow was on.
I would consider it. It’s somewhere in the $8,000 range and our first shot out of the gate I didn’t want to spend that much to evaluate everything. With Collector now supporting GNSS receivers, I would consider it a little harder. The amount of time I have to wait to acquire accuracy is one of the most important aspects to me when gathering points. If it worked as well as our Arrow 100 and provided a little more accuracy when not connected to an RTK network, then I would definitely consider it on our next purchase.


Q33: How long did you have to stand at a point to get the high accuracy when you were close to trees or mirrored buildings?
A33: We have really only had one instance when our accuracy was really compromised and that was when we were close to a heavy stand of pine trees that were on our west and southwest side. At least I think that was the culprit. We went out twice to same location and had similar effects on the accuracy. We were not connected to an RTK network, and the horizontal accuracies were around a few meters. It’s the only time I have seen it happen. I have heard that pine trees cause the most interference of any trees. Based on our experience I believe it.
Buildings aren’t an issue for us since we are pretty rural. But, I would think if you are near buildings you are going to have access to the internet and an RTK network, which should help with that issue.


Q34: What are the percentage of points taken that are under a foot with this setup?
A34: That one’s tough because we are a rural system. If we had a good data connection all day, if we were in town for example, I would be fairly confident that every point we take would be sub-foot. But when we lose that data connection, we have to rely on the differential correction from the receiver. While it definitely provides correction, and improves the receiver’s accuracy, you’ll be looking at sub meter performance. Although, I have gotten to 1 foot accuracy just on the receivers correction when I’m here at our water plant. It’s wide open with no trees or interference.

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