WEBVTT 00:00:00.280 --> 00:00:02.280 Welcome to OPUS Projects Training. 00:00:02.759 --> 00:00:05.660 In this module, we will discuss the development of the 00:00:05.710 --> 00:00:09.460 survey scheduled, giving due consideration to network design and other 00:00:09.520 --> 00:00:10.000 criteria. 00:00:10.600 --> 00:00:13.399 If you intend to submit your project to NGS for 00:00:13.460 --> 00:00:17.280 publication, it's important to note that the survey schedule and 00:00:17.340 --> 00:00:20.560 final network map must accompany the project proposal. 00:00:22.400 --> 00:00:25.470 Please note the current version of OPUS Projects may look 00:00:25.530 --> 00:00:28.600 slightly different than the screens in this presentation. 00:00:29.360 --> 00:00:31.840 The functionality generally remains the same. 00:00:33.680 --> 00:00:36.810 In this module, we will discuss which marks you may 00:00:36.870 --> 00:00:40.370 want to include in an observation session and the reasons 00:00:40.440 --> 00:00:43.630 for doing so, how you design your network, plan your 00:00:43.690 --> 00:00:48.790 occupations, choose session durations, number of occupations, baseline length, ties 00:00:48.850 --> 00:00:51.000 to passive marks, and other topics. 00:00:52.080 --> 00:00:55.780 Knowing what resources are available, you can start designing efficient 00:00:55.830 --> 00:00:57.240 and effective observations. 00:00:57.880 --> 00:01:01.340 We will of course, discuss some field constraints, like how 00:01:01.400 --> 00:01:04.450 long it takes to drive between Marks, and we'll also 00:01:04.510 --> 00:01:06.800 touch on site security and site safety. 00:01:09.200 --> 00:01:13.220 Understanding how processing is done within OPUS Projects informs your 00:01:13.280 --> 00:01:16.900 planning and helps ensure that your observations will meet your 00:01:16.959 --> 00:01:17.880 project's needs. 00:01:20.120 --> 00:01:23.720 It's important to understand how PAGES, which is the baseline 00:01:23.780 --> 00:01:27.970 processing engine in OPUS Projects, works compared to commercial vendor 00:01:28.030 --> 00:01:31.040 processing software with which you may be familiar. 00:01:32.360 --> 00:01:37.680 Let's consider creating a session using 4 receivers that develops 00:01:37.760 --> 00:01:42.500 3 independent or non trivial baseline, shown here as solid 00:01:42.590 --> 00:01:46.430 blue lines. That would be equal to the number of 00:01:46.510 --> 00:01:48.560 receivers -1. Using PAGES. 00:01:48.880 --> 00:01:52.470 There are other correlations that exist, shown here as dashed 00:01:52.530 --> 00:01:53.120 red lines. 00:01:53.760 --> 00:01:56.720 PAGES computes and provides that information. 00:01:57.720 --> 00:02:01.010 But if you went out and observed 3 independent baselines 00:02:01.060 --> 00:02:04.700 with your vendor software, you would not have the correlations 00:02:04.760 --> 00:02:07.700 between all the marks. With PAGES and the fact that 00:02:07.760 --> 00:02:10.870 we suggest using the hub type strategy, you will have 00:02:10.919 --> 00:02:12.040 those correlations. 00:02:12.919 --> 00:02:16.510 There are different combinations of independent vectors that one could 00:02:16.560 --> 00:02:19.290 choose to process, and then you'd get a different set 00:02:19.340 --> 00:02:20.160 of correlations. 00:02:26.080 --> 00:02:30.630 Let's compare the main differences between baseline solutions and session 00:02:30.700 --> 00:02:31.320 solutions. 00:02:31.960 --> 00:02:36.720 A baseline solution computes 1 baseline at a time, includes 00:02:36.790 --> 00:02:42.030 all independent and dependent baselines for each session equal to 00:02:42.120 --> 00:02:42.760 n times n -1 00:02:42.760 --> 00:02:43.679 over 2. 00:02:44.960 --> 00:02:49.820 Ignores the mathematical correlations between baselines which were observed in 00:02:49.889 --> 00:02:53.750 the same session, and must be properly scaled before combining 00:02:53.820 --> 00:02:56.000 sessions into a network adjustment. 00:02:57.440 --> 00:03:03.750 A session solution computes simultaneous processing of all independent baselines 00:03:03.830 --> 00:03:08.480 with the mathematical correlations between those baselines. 00:03:08.760 --> 00:03:13.019 It includes only the independent baselines, of which there are 00:03:13.090 --> 00:03:15.970 only n -1, and it is ready for combining 00:03:16.040 --> 00:03:17.760 into network adjustments. 00:03:20.080 --> 00:03:23.260 Looking back, we might have drawn a network diagram showing 00:03:23.310 --> 00:03:26.000 the local baselines that we wanted in our project. 00:03:27.400 --> 00:03:31.220 In order to build that with four receivers, we would 00:03:31.290 --> 00:03:36.070 process these three independent vectors in the first session, and 00:03:36.140 --> 00:03:39.810 in the second session we'd process these 3, and so 00:03:39.880 --> 00:03:44.440 on, picking up three independent vectors in each session until 00:03:44.510 --> 00:03:48.550 we've completed the figure that we intended to survey 6 00:03:48.620 --> 00:03:49.800 sessions in all. 00:03:58.040 --> 00:04:01.080 But in OPUS Projects, we don't think about the individual 00:04:01.130 --> 00:04:02.680 vectors between the stations. 00:04:02.680 --> 00:04:06.180 Instead, we focus more on which stations we are observing 00:04:06.240 --> 00:04:10.670 simultaneously, because we know that if we observe those simultaneously, 00:04:10.730 --> 00:04:14.540 we're going to get all the connections either directly through 00:04:14.600 --> 00:04:16.880 a vector or through the correlations. 00:04:24.010 --> 00:04:28.470 By default, OPUS Projects will create independent baselines for each 00:04:28.529 --> 00:04:31.810 session from a single hub, like spokes in a wheel. 00:04:32.330 --> 00:04:36.490 Generally speaking, OPUS Projects will select the most central CORS 00:04:36.550 --> 00:04:39.920 with respect to the local project area and designate it 00:04:39.980 --> 00:04:40.529 as a hub. 00:04:41.320 --> 00:04:44.390 The relationship between all of the non hub marks are 00:04:44.450 --> 00:04:47.760 going to be represented by the mathematical correlations. 00:04:48.360 --> 00:04:51.100 Those are the other connections that you don't see on 00:04:51.150 --> 00:04:52.440 the map, but which exist. 00:04:52.880 --> 00:04:55.410 And again, this has some benefits in the way that 00:04:55.460 --> 00:04:56.600 the data is processed. 00:04:57.320 --> 00:05:00.420 Let's look at our example using the OPUS Projects PAGES 00:05:00.480 --> 00:05:03.360 approach with our hub in the middle of the project. 00:05:03.680 --> 00:05:06.620 I know that if we observe these four stations in 00:05:06.680 --> 00:05:10.540 the first session, these are the three independent vectors that 00:05:10.600 --> 00:05:14.220 we're getting, the solid blue lines and we're getting these 00:05:14.279 --> 00:05:15.080 correlations. 00:05:15.080 --> 00:05:19.170 Also the dashed blue lines in the second session, these 00:05:19.240 --> 00:05:21.400 are the marks being observed. 00:05:21.839 --> 00:05:25.660 These are the independent vectors that are being produced, and 00:05:25.720 --> 00:05:28.000 these are the correlations and so on. 00:05:28.000 --> 00:05:29.600 Through all six sessions. 00:05:30.480 --> 00:05:33.360 The mark to mark relationship that you want is being 00:05:33.420 --> 00:05:36.520 generated, even though you don't see that on the screen. 00:05:41.480 --> 00:05:44.440 See the sample OPUS project session inset. 00:05:45.160 --> 00:05:48.210 It's important for you to know what you're getting so 00:05:48.260 --> 00:05:51.600 that you can plan your project and observations correctly. 00:05:53.920 --> 00:05:56.089 Let's move on to which marks you would want to 00:05:56.140 --> 00:05:57.560 observe together in a session. 00:05:59.520 --> 00:06:02.130 There are a few rules of thumb. Marks that are 00:06:02.180 --> 00:06:05.250 intervisible, meaning that you can see from one mark to 00:06:05.310 --> 00:06:07.980 the next, or where the intent of the two marks 00:06:08.029 --> 00:06:08.960 is to establish. 00:06:09.000 --> 00:06:11.540 a mark and a back sight, should be observed in 00:06:11.600 --> 00:06:14.710 the same session as opposed to being in two independent 00:06:14.770 --> 00:06:15.279 sessions. 00:06:16.360 --> 00:06:18.730 Any group of marks for which you want the best 00:06:18.779 --> 00:06:21.930 local accuracy need to be observed simultaneously so that you 00:06:21.980 --> 00:06:24.920 have a direct relationship between them and which will be 00:06:24.970 --> 00:06:26.360 reported in the adjustment. 00:06:27.800 --> 00:06:30.660 Points that are intended to be the beginning and ending 00:06:30.710 --> 00:06:33.720 control points of a future traverse or other survey should 00:06:33.770 --> 00:06:36.830 be observed simultaneously so that there is a good internal 00:06:36.880 --> 00:06:38.080 precision between them. 00:06:38.720 --> 00:06:41.890 Really any place where you want to maximize the internal 00:06:41.950 --> 00:06:46.479 precision, especially vertical control points and their near neighbors, bringing 00:06:46.540 --> 00:06:50.620 that information directly into your project through shorter, more direct 00:06:50.680 --> 00:06:51.360 connections. 00:06:53.200 --> 00:06:58.510 A new set of standards and specifications to support OPUS 00:06:58.610 --> 00:07:04.020 Projects called NOS NGS 92 has been written to replace NOS 00:07:04.110 --> 00:07:05.880 NGS 58 and NOS NGS 59. 00:07:06.480 --> 00:07:11.300 The new standards and specifications include session length, number of 00:07:11.370 --> 00:07:16.600 occupations, repeat occupation criteria, baseline length and ties to passive 00:07:16.670 --> 00:07:17.080 marks. 00:07:19.120 --> 00:07:22.050 Here we can see that depending on the classification and 00:07:22.100 --> 00:07:24.400 survey method, there are different criteria. 00:07:25.040 --> 00:07:28.900 For example, a primary survey that uses the OPUS Projects 00:07:28.970 --> 00:07:33.110 post processing method can have vectors up to 200 kilometers, 00:07:33.180 --> 00:07:36.230 but each mark requires a total of 20 hours of 00:07:36.300 --> 00:07:40.840 occupation with recommended session durations of ten, seven or five hours 00:07:40.910 --> 00:07:45.250 regardless of vector length, and at least one repeat observation 00:07:45.320 --> 00:07:47.960 has to be conducted on a different day. 00:07:48.560 --> 00:07:53.200 Also notice that the criteria for repeat observations requires that 00:07:53.270 --> 00:07:56.520 the start times be offset by three to 21 hours. 00:07:57.560 --> 00:08:02.400 The secondary and local classifications will allow shorter duration sessions 00:08:02.460 --> 00:08:05.200 and in some cases allow fewer observations. 00:08:05.520 --> 00:08:08.230 This is a function of the accuracy standard for each 00:08:08.280 --> 00:08:09.480 of the classifications. 00:08:10.120 --> 00:08:13.940 As the required accuracy goes down, the criteria can get 00:08:14.010 --> 00:08:14.560 relaxed. 00:08:15.320 --> 00:08:17.950 So, as you can see, the standards play a direct 00:08:18.010 --> 00:08:20.920 role in the development of the observation schedule. 00:08:23.320 --> 00:08:27.320 In addition to the session length criteria is the requirement 00:08:27.390 --> 00:08:28.960 for repeat observations. 00:08:29.720 --> 00:08:33.679 Each of the classifications will specify the number of repeat 00:08:33.740 --> 00:08:38.220 observations, any required time offset for these observations, and in 00:08:38.280 --> 00:08:42.300 some cases, whether the repeat observations need to take place 00:08:42.370 --> 00:08:43.600 on a different day. 00:08:44.559 --> 00:08:47.679 The purpose of the time offset is to ensure that 00:08:47.750 --> 00:08:51.970 different satellites are observed in each session and to mitigate 00:08:52.040 --> 00:08:54.120 short term multipath conditions. 00:08:55.320 --> 00:08:59.360 Observations on different days are generally required for static and 00:08:59.420 --> 00:09:03.100 real time surveys on our intended to sample observations taken 00:09:03.160 --> 00:09:05.480 under different atmospheric conditions. 00:09:06.640 --> 00:09:10.150 The standard time offset for a repeat observation is three 00:09:10.210 --> 00:09:13.400 hours before or after the start time of the first 00:09:13.460 --> 00:09:14.240 observation. 00:09:15.480 --> 00:09:18.650 Observations that are five or more hours in length do 00:09:18.710 --> 00:09:22.640 not require the three hour offset, but do require observations 00:09:22.700 --> 00:09:23.840 on different days. 00:09:24.559 --> 00:09:27.840 Here we can see an example of how one might 00:09:27.920 --> 00:09:33.110 conduct repeat observations for a static session being conducted for 00:09:33.179 --> 00:09:38.070 a primary classification survey, and here's an example of repeat 00:09:38.140 --> 00:09:42.800 observations being conducted for a secondary or local survey. 00:09:43.280 --> 00:09:46.520 Since the observations are less than five hours in length, 00:09:46.580 --> 00:09:49.150 there needs to be at least a three hour offset 00:09:49.210 --> 00:09:50.440 in the starting times. 00:09:50.880 --> 00:09:53.200 This can be done in one day if possible, or 00:09:53.260 --> 00:09:54.880 can be done on different days. 00:09:55.520 --> 00:09:58.210 Notice that even when the observation is done on a 00:09:58.260 --> 00:10:01.059 different day, the start time is still offset by the 00:10:01.110 --> 00:10:01.760 three hours. 00:10:04.600 --> 00:10:08.610 Some other considerations when developing your network design and schedule 00:10:08.660 --> 00:10:11.800 are the available resources, both equipment and personnel. 00:10:12.840 --> 00:10:15.710 Do you have 100 receivers at your disposal or only 00:10:15.760 --> 00:10:16.280 a couple? 00:10:18.200 --> 00:10:20.280 How many field observers are available? 00:10:20.720 --> 00:10:24.290 Are the same or different numbers of observers available every 00:10:24.350 --> 00:10:25.440 day of the project? 00:10:25.840 --> 00:10:29.559 Are there certain marks that might require specific observers or 00:10:29.620 --> 00:10:30.720 specific equipment? 00:10:31.320 --> 00:10:34.230 Maybe there's a hike required to access a mark, and 00:10:34.280 --> 00:10:37.760 maybe there's an observer better suited for making that hike. 00:10:38.720 --> 00:10:41.790 Maybe a four wheel drive vehicle is required for some 00:10:41.850 --> 00:10:44.400 observations and not every observer has one. 00:10:45.240 --> 00:10:48.040 Or maybe special equipment is needed to set up on 00:10:48.100 --> 00:10:51.190 a certain mark, whether it be taller than normal setup 00:10:51.250 --> 00:10:54.450 to get above obstructions or some special type of tripod 00:10:54.510 --> 00:10:57.370 or mounting for setting up on marks that cannot be 00:10:57.420 --> 00:11:00.000 observed with a standard fixed height tripod. 00:11:02.080 --> 00:11:05.250 Finally, we need to consider any field constraints that might 00:11:05.300 --> 00:11:07.480 affect the schedule or the network design. 00:11:07.920 --> 00:11:11.600 Some common considerations are how long it takes to travel 00:11:11.660 --> 00:11:14.640 between stations, site access, and site safety. 00:11:16.000 --> 00:11:18.950 If you're observing more than one session in a day, 00:11:19.010 --> 00:11:22.309 you need to consider what kind of field constraints there 00:11:22.370 --> 00:11:25.840 might be when traveling between and from station to station. 00:11:26.679 --> 00:11:29.260 Do you have to deal with traffic or various speed 00:11:29.309 --> 00:11:29.679 limits? 00:11:29.840 --> 00:11:32.360 Is off road travel or hiking required? 00:11:32.760 --> 00:11:35.830 The intent of an observation session is to have all 00:11:35.890 --> 00:11:38.840 participating receivers operating simultaneously. 00:11:39.760 --> 00:11:42.950 To that end, it is imperative to develop the schedule 00:11:43.010 --> 00:11:46.559 so that all observers can start and stop their observations 00:11:46.620 --> 00:11:48.480 at approximately the same time. 00:11:49.160 --> 00:11:52.880 Remember, it is not just important that each observer collects 00:11:52.940 --> 00:11:54.679 the prescribed hours of data. 00:11:55.160 --> 00:11:58.420 It is also important that all receivers in the session 00:11:58.480 --> 00:12:02.520 have that many hours of simultaneous or overlapping data collected. 00:12:03.160 --> 00:12:06.590 The observation schedule needs to be developed such that it 00:12:06.650 --> 00:12:10.660 accommodates the observer with the longest travel time, ensuring that 00:12:10.720 --> 00:12:14.559 all observers can collect the required amount of overlapping data. 00:12:17.440 --> 00:12:20.120 Another consideration is site access. 00:12:20.520 --> 00:12:23.840 Are there restricted hours or specific days when the site 00:12:23.900 --> 00:12:24.720 is accessible? 00:12:25.120 --> 00:12:27.470 Can you drive to the station on some days or 00:12:27.520 --> 00:12:28.640 times but not others? 00:12:29.200 --> 00:12:31.200 Do you have a high tide situation? 00:12:33.640 --> 00:12:37.200 And finally, consider the security of your personnel and equipment. 00:12:37.600 --> 00:12:40.290 If you're setting up for long occupations and you leave 00:12:40.340 --> 00:12:42.929 the equipment unattended for a period of time, do you 00:12:42.980 --> 00:12:44.400 have to worry about security? 00:12:44.760 --> 00:12:47.070 Is the site in a place where you feel safe 00:12:47.120 --> 00:12:49.929 leaving it unattended, or do you have to consider a 00:12:49.980 --> 00:12:52.400 method of securing it with cables and locks? 00:12:53.080 --> 00:12:56.200 Maybe you just have to plan to have your personnel 00:12:56.260 --> 00:12:57.760 on site the entire time. 00:12:59.920 --> 00:13:03.160 Once you've addressed all these considerations, you can begin to 00:13:03.210 --> 00:13:04.320 develop your schedule. 00:13:05.880 --> 00:13:09.830 In this example, we have a small project with five 00:13:09.910 --> 00:13:12.600 stations, not counting Mark GP 99. 00:13:13.760 --> 00:13:17.090 We're planning to conduct a local survey and we will 00:13:17.160 --> 00:13:18.440 run 3 hour sessions. 00:13:19.120 --> 00:13:22.480 We have 3 receivers available to us, so we'd be 00:13:22.550 --> 00:13:26.199 able to observe one 3 hour session in red and another 00:13:26.270 --> 00:13:30.200 three hour session in blue depending on the travel time 00:13:30.280 --> 00:13:30.920 required. 00:13:31.440 --> 00:13:34.180 In this case, the travel time is short and we 00:13:34.240 --> 00:13:36.560 can observe 2 sessions, A and B, in one day. 00:13:37.800 --> 00:13:41.069 We've determined which marks we want to be observed in 00:13:41.130 --> 00:13:44.580 the same session and have assigned marks to each observer 00:13:44.650 --> 00:13:48.160 for each session and entered that into the scheduled grid. 00:13:48.720 --> 00:13:51.690 We can start by assigning the start and end times 00:13:51.750 --> 00:13:53.080 for the first session. 00:13:54.080 --> 00:13:57.010 Then we add our travel time, 1/2 hour in this 00:13:57.080 --> 00:14:00.470 case, and determine the start and stop times for the 00:14:00.540 --> 00:14:04.640 second session and this would complete the observations for the 00:14:04.710 --> 00:14:05.360 first day. 00:14:06.640 --> 00:14:09.920 Since we need one set of redundant observations for a 00:14:09.980 --> 00:14:13.450 local survey and these observations need to be offset by 00:14:13.510 --> 00:14:16.800 three hours, we will choose to observe the second day 00:14:16.860 --> 00:14:19.950 in reverse order from day one, giving us the three 00:14:20.020 --> 00:14:20.760 hour offset. 00:14:23.320 --> 00:14:25.400 Repeat the process for the next day. 00:14:25.440 --> 00:14:28.120 Stagger the start time by three hours if it is 00:14:28.180 --> 00:14:29.400 a repeat observation. 00:14:29.880 --> 00:14:33.150 And remember, if you're planning to submit your project to 00:14:33.210 --> 00:14:36.700 NGS for publication, a copy of your final observation schedule 00:14:36.760 --> 00:14:39.860 and network map will be included as attachments to your 00:14:39.920 --> 00:14:40.880 project proposal. 00:14:42.120 --> 00:14:45.200 This concludes the module on developing the survey schedule.