Cleaning multibeam data with S-CAN in NaviEdit and NaviModel

Transcription

1 Cleaning multibeam data with S-CAN in NaviEdit and NaviModel Revisions JEK Initial Version Introduction This document describes how to use S-CAN in NaviModel. It s a walkthrough that takes you through reading data from NaviEdit into NaviModel, cleaning the data, and writing the result back to NaviEdit. Reading data from Naviedit 1) Start NaviModel, and connect to NaviEdit, by choosing File->Connect to Naviedit. 2) NaviEdit database shows up in project tree, as in the Naviedit JobPlanner.

2 3) Right click a folder to Add survey data. This adds survey soundings to a new DTM that will be created. 4) Pick the blocks you want in the DTM. You can safely add all blocks at once, unless you have blocks that you know are not suitable for a DTM. There is no limit to the size of the DTM we are generating. 5) In the DTM settings box, click Auto detect button to find a decent cell size of the DTM you want to create. After a little while, the Cell size box will be filled with the recommended cell size. You are free to choose another path and filename of the new DTM, please keep the.db extension. For best performance we recommend using a fast local harddrive, solid state disks have proven to have very good performance.

3 6) Click ok, and the program starts indexing the files into a dtm. In the lower right corner of the statusbar, you can follow progress on indexing. Indexing is the process of creating the DTM. The indexing job reads block from NaviEdit and creates a DTM model in an SQLite database. Soundings are added to the DTM, and grid models in different resolutions are calculated to help performance of viewing. 7) You can also follow progress in the Job List window. Choose View->Job List to open the window. This window lists jobs in queue. Lengthy operations typically run as a job in this list. S-CAN will also run here. You can freely fly around in the 3D view event when jobs are running. If the queue is long, you can check the Play sound box, to have a sound played when last job finishes. This way, you can do something else while waiting, and get notified when done.

4 8) When the indexing has finished, you see the new DTM in the project tree. Opening the DTM nodes in the tree shows from which files the DTM was made. In our case it is the blocks of our NaviEdit database. Selecting each block in the DTM outlines the bounding box of its location. 9) Double click somewhere in the model, then use mouse wheel to get closer to the terrain. Click the raw points button in the toolbar to enable raw points in the 3D view. Blue points are filtered points, that cannot be edited. They will have to be changed in the NaviEdit header editor. Open the View->Settings window to change the raw points cvolor mode to Depth. The range of the rainbow can be changed using the slider window that pops up. The palette is centered around the target point in the middle of the screen. Fly around looking at raw points using a 3D mouse and mouse wheel (We recommend Space Navigator), keys ADWSQERV or arrow keys. Switch off the raw points on the toolbar button.

5 Cleaning with S-CAN SCORE 1) Open the point cleaning toolbox from the View menu. This opens a set of tools for cleaning. You might want to have this toolbox opened when you are cleaning data. Available are a set of tools that can be used in different situations. Among those are the S-CAN automatic cleaning tools. 2) Click the S-CAN Score button in the cleaning toolbox. Then click a polygon around an area for which you want tocalculate a score value for each sounding. End the polygon with double click at the last point. You can also click a polygon around the entire model.

6 3) Now a score is calculated for each sounding in the area you picked. Nothing in the DTM is changed yet. Check the Close window when done, leave the process alone and do something else. 4) When done, NaviModel reads back the results and creates a new database of score values next to the DTM model on the disk. The read-back process creates a Score patch on the disk 5) The score patch is placed next to the DTM model. It gets the same name as the DTM model, but with a time and score.patch extension to it. The patch contains a score value for all soundings in the selected area

7 6) The patch also gets represented under the DTM model node, in the Filtered Regions folder. Selecting the patch in the tree, outlines the area in the 3D Model. The patch has a set of properties and information that can be seen in the properties window below. 7) To clean the area, right click the Score node and select Clean Area (Polygon). This is used to click a polygon inside the filtered area for which you want to apply a score threshold value. If you calculated score for the entire dataset, you may want to apply different score thresholds in different areas. Therefor you can click a polygon for a particular area and choose a threshold value for that. You can also choose to clea the entire area with the same score value.

8 8) In this image, I clicked the yellow area. A threshold slider comes up, where I can choose an acceptable score value. Points that have lower score than chosen in the slider gets red. You can adjust the slider, and see what gets cleaned in real time. You can use middle mouse button to pan around in the selected area. Use mouse when to getting closer. That in combination with using the slider allows you to find a good threshold value. Nothing is changed in the DTM before you click ok. The blue points are not affected. The were already filtered off in the NaviEdit header editor. 9) Click ok in the slider window to apply the select threshold value. The red soundings are marked deleted in the DTM, and new grid maps are calculated, ignoring the points marked deleted. The cleaned area is listed in the Cleaned regions node in the tree. A cleaned region has information about the cleaning in the properties window.

9 Cleaning with S-CAN Components 1) Open the Point Cleaning Toolbox from the View menu, click C-SCAN Components to activate the tool. 2) Click a polygon around an area you want cleaned, end with a double click

10 3) Enter values in the Input Values box. Treshold is the size at which components are split. If you are looking for small things, make a small threshold value. Surfaces is the number of surface you want calculated at max. If there are more than n surfaces, the smallest are collected in a Remaining surface node. 4) Click ok, and the Components calculation starts running. Nothing is changed in the DTM yet.

11 5) Click OK in the S-CAN box when done. NaviModel takes the results and build a components patch next to the DTM model. This patch contains information for each sounding in the selected area. 6) The patch is represented int the Filtered node under the DTM model in the project tree. Information about what was calculated is seen in the properties window below.

12 7) Right click the Components node to clean the entire area. A surfaces box comes up in where you can toggle components (surfaces) on/off. You can click the check boxes in the Surfaces box, or you can click on a point in the 3D window. By default everything is switched off, but the largest component which is typically the seabed. You can double click on a component ni the surfaces window to fly to it. 8) Click OK in the Surfaces box, and NaviModel marks the points of the un-selected surfaces as deleted. Then it recalculates the DTM model, ignoring deleted points. 9) In the project tree, you see the cleaned regions under the DTM node. In the properties of the DTM, you can change the color mode to cleaned regions, this shows where you have already been cleaning.

13 Writeback to NaviEdit 1) When you have cleaned the DTM model, you can write the result back to the Naviedit SQL database. Click the Save to NaviEdit button in the Cleaning Toolbox. 2) Select the block you want written back. If you have only cleaned a small area, you may want to only writeback a few blocks.