3 Navimodel tools that can simplify a Data Processor’ s life

by Umberto on 11 November, 2020 in Offline

As a Data Processor I love EIVA Navimodel, since some Navimodel tools and utilities helped me save hours and hours of work.

I have always said it to any person I worked with and I will continue to do so (as long as it remains the most powerful processing software for MBES survey and point clouds out there).

But three Navimodel tools made me always think they were a step ahead of others.

Want to find out which?

Follow me.

The three Navimodel tools that will ease your processing job

These powerful tools I’m going to talk to you about are:

  • Level Out
  • Match Up
  • Rectify

All of them can be easily found in the Navimodel Contextual Menu (right-click) on the DB name, under the Modify Points Submenu, as shown in the picture below.

Navimodel tools location

Location of the Navimodel tools metioned

 And each of them, used in the right way, can help you solve big issues with little-to-no stress.

Let’s dig into details of what each tool does and how.

Level Out: How to eliminate height differences between datasets

Level Out, as you can imagine, comes in handy when you have some datasets that do not match on the Z-axis.

But be Aware. I’m not talking about Tide errors. For that kind of error, you have to go back to NaviEdit. The Level Out tool can move a dataset only entirely and not based on time/space.

You can see it clearly in the image below.

What does the Level Out do?

The Level Out tool analyzes the DTM model in some sampling points (chosen based on settings decided by the user) and calculates a mean surface between all the datasets.

After this, the tool calculates which is the mean shift to apply to each dataset to reduce the height gap to a minimum, and lastly, it applies it.

Note:  The Level Out tool will apply the same Z shift to the whole block (dataset part/file)

How does the Level Out work?

Level Out application examples

Which are the Level Out Steps?

Level Out - Step 1

Launch the Level Out Tool.

Level Out - Step 2

Set the sampling parameters in the dialogue box that appears.

Level Out settings

Level Out Settings

Level Out - Step 3

Wait for the tool to complete the calculations and the surface creation.

Level Out - Step 4

Compare the new surface with the old one.

Level Out - Step 5

If the result is not acceptable repeat steps from point 1.

Level Out - Step 6

If you are happy with the final result, then congratulations. Job Completed

Match Up: Your savior when you have navigation errors and artifacts on a pipeline survey

Imagine having surveyed a 30” pipeline and your DTM goes left and right like a professional skier during the world championship on the Alps.

What do you do?

Ask help to the Match Up tool!

What does the Match Up do?

It lets you revert the effect of poor navigation using some stable references. For example, the 30” I mentioned earlier. It for sure, since its diameter, is quite straight, therefore it could be used as a reference.

Note: the Match Up is mainly meant to be used with linear features (pipes etc) as reference.

Using two digitized lines (one from the Raw track/navigation and another one for the corrected pipeline route) the Match Up tool moves parts of DTM to place them in their correct position.

Be aware that the only movement this tool is allowed to make is on the cross-sectional plane. This means that, even if your digitized lines have different Z values, these will be totally ignored.

Navimodel tools: How does the Match Up work?

Match Up application explanation

Which are the Match Up Steps?

Match Up - Step 1

Backup the original database.

Match Up - Step 2

Import the track of the object that performed the survey and save it as a digitized line (I suggest to use “RAWXX-Line name” where XX is an incremental number like 01/02 if you may want to keep track of various modifications you may do while saving the original one).

Match Up - Step 3

Duplicate the line, rename it (I suggest to use “PROCXX-Line name” where XX is in incremental number like 01/02 if you may want to keep track of various modifications you may do while saving the original one), and smooth it to an acceptable result.

Match Up - Step 4

Run the Match UP tool.

Match Up - Step 5

Select the blocks (that’s how Navimodel calls the raw files that originate the DTM) you want to correct by using this tool.

Match Up settings 1

Match Up Settings (1 of 2)

Match Up - Step 6

In the upper box select the Reference Line (RAWXX-Line name).
In the lower box select the destination line (ProcXX-Line name).

Match Up settings 1

Match Up Settings (2 of 2)

Match Up - Step 7

Press Ok. Sit and wait.

Match Up - Step 8

If the result is not acceptable reimport the original DB and repeat all the sequence from Match Up - Step 1.

Match Up - Step 9

If you are happy with the final result, then congratulations. Job Completed.

Lifesaver Advice - Backup & Match Up

It is of vital importance to remember to back up the data before using the Match Up tool.

Apart that it is anyway the best practice, this recommendation is due for the way this Navimodel tool works.

If you forget to backup it and you are not happy with the final result, there is no way back. You will have to start again from the raw files.

Why?

Because, once it starts processing the dataset, it moves all the points of the dataset from the original blocks (files/parts) to a new one called MatchUp.xyz.

And if, by error, you remove that block from the dataset you have lost everything.

Rectify: Manipulate your MBES data to overcome errors and display the truth

Imagine having really awful navigation (maybe USBL) and, even after some NAV despiking and smoothing, your MBES data still look like a train wreck.

What do you do?

Go there and repeat the survey? Probably this is not a viable option.

So? Do you summon a VooDoo spell on your data hoping for the best?

Been there. Done that. I can assure you this doesn’t work.

But you can still try to use the Rectify tool.

What does the Rectify do?

Rectify is the most powerful of these three Navimodel tools and, to some extent, it works similarly to the Match Up tool.

It needs two lines as well to modify the data, but it can modify the data on any axis and by any scale.

Just think of any kind of useful transformation you may need to apply to your DTM, Rectify can probably do it.

  • Stretch
  • Shrink
  • Curve
  • Straighten
  • Steepen
  • Flatten
Navimodel tools: How does the rectify work?

Rectify application explanation

Be Responsible when using Rectify

As Spiderman would also say “from great powers come great responsibility”, so you have to be really thoughtful when using this tool.

It should be used only to display the truth hidden from some, otherwise inevitable, instrumental failures.

No other cases should be allowed.

Do you have troubles finding a good example? I will give you one.

We were working with some AUV data recorded using QINSy. Unfortunately, its INS, since it wasn't USBL aided suffered of some drift. We couldn' t correct the datasets using Naviedit but we found another way around.

Using the Delta X and Delta Y values of the drift and applying them using the Rectify, we were able to correct the DTM, placing the data in its real position.

Contrarly to the Match Up tool , Rectify will create a brand new database leaving the original one untouched.

This gives the Data Processor the serenity to try it all the time he wants without the worring of compromising hours of work.

Which are the Rectify Steps?

Rectify - Step 1

Create the first digitized line either by importing the track or by drawing it on screen.

Rectify - Step 2

Create the second digitized line either by duplicating the first one and modifying it or creating it from scratch

Rectify - Step 3

Run the Rectify tool.

Rectify - Step 4

In the upper box select the Reference Line (RAWXX-Line name).
In the lower box select the destination line (ProcXX-Line name).

Rectify Settings

Rectify Settings

Rectify - Step 5

Press Ok. Sit and wait.

Rectify - Step 6

If the result is not acceptable repeat all the sequence from Rectify - Step 1.

Rectify - Step 7

If you are happy with the final result, then congratulations. Job Completed.

Note: After some reiteration the rectify tool may “crash” and return the same results even with different lines.

Simply close and restart Navimodel to solve this.

Conclusion on these Navimodel tools

These are my considerations on what I think are some of the most powerful processing tools for MBES survey at the moment.

These EIVA Navimodel Tools, if used correctly, can overcome the incoveniences of any instrument failure and speed up the delivery process.

If you haven' t tried them yet I highly encourage you to do so.

Now you have 2 options:

  1. If you have any question or doubt about these Navimold tools I presented you feel free to shoot me a comment below. I will answer it personally!
  2. Or If you simply liked the article you can share it (using one of the buttons you can see on the left here) so that it may be useful to some other surveyors like us.

See you in the next posts fellow Smartest Surveyor.

Umberto


Tags

MBES Processing, Navimodel, Software


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