The Space Warp module combines three different functions for simple and fast unfolding of irregular-shaped surfaces.
The functions “Cylindrical section”, “Polygonal section” and “Curved section” can be used or example to analyze liquid tanks, angled walls, sloping roof surfaces, curved house facades and walls as orthophotos.
Cylindrical Section
The cylindrical section is particularly suitable for displaying a tower or channel access as a 2D orthophoto, for example. The results can be further used for surface inspection. In a tower the cylindrical section tool can be used to inspect the stones and see if any are missing. The entire surface of the tower can thus be measured much faster and more efficiently without the need to create a large number of individual sections.
To start the tool, select the “Cylindrical section”. The surface of the cylinder can be defined as an ellipse with at least 5 control points. In the corresponding view, in this case the Top View, click at least 5 points on the required cylinder shell one after the other. From the fifth point an ellipse is automatically estimated.
End the ellipse definition with a double click on the last point. These points can still be adjusted after you have finished defining the ellipse. The ellipse is estimated and visualized in real time.
The yellow highlighted sectional area defines the area of the point cloud included in the calculation of the cylindrical section. The section area can be adjusted as needed in the Top View. In this example, the height of the cylinder can be edited in the Front View.
Like a planar section, the cylindrical section also has a viewing direction that is represented by the arrow symbol. In the Job Editor you can reverse the viewing direction by clicking the “Flip View” button.
Implicitly the left and right side of the unfolded surface is swapped. Use the color or intensity information to colorize the resulting orthoimage. To unfold the inner surface, like in this example, the direction of projection should point from inside to outside.
After customizing all the other options such as resolution, intensity and color values, the process can be started. For a more detailed explanation of the setting options, see the Tutorial Processing Parameters
The result of the cylindrical section can be opened with a double-click on the entry in the Job-List or with a right-click on the element by selecting Open from the context menu.
Polygonal Section
With the “Polygonal section” function, all the irregular surfaces of a façade can be displayed as a 2D orthophoto in one-go. The results are planar orthophotos, in which measurements can be carried out quickly, without the need of creating a large number of individual sections.
Activate the “Polygonal section” tool. Define the area of interest in the Standard Top View. Set the first point of the section and insert another corner point each time you click the left mouse button. Double-click to end the section:
The yellow marked area defines which points of the point cloud are included in the unfolding process. It is still arbitrarily adaptable, each control point can be moved individually in the View where the area was defined. The extent of the selection can be adjusted manually using the blue arrow keys in all three standard views. As in a normal planar section, the polygonal section also has a viewing direction represented by the arrow symbol.
In the Job Editor, you can reverse the viewing direction by clicking the “Flip View” button. Implicitly, the left and right sides of the unfolded surface are swapped. If the color or intensity information of the scan data are used, the corresponding surface information from the outside or from the inside will be displayed. To display the external facade of the building as a planar orthophoto, the viewing direction should point from the outside to the inside.
After customizing all further settings, such as resolution, intensity or color values, the calculation can be started by clicking on the green start button in the Job List. A detailed explanation of the individual setting options in the Job Editor can be found in the tutorial Processing Parameters.
The result can be open with a double click on the calculated job in the Job List or with a right-click on the element by selecting Open from the context menu.
Ergebnis des polygonalen Schnittes in PointCab
This tool can be used similarly in every floor plan or section. Now it is possible to display for example tilted roof surfaces as 2D orthophotos much more easier. Define a polygonal section in a facade view, in the roof area.
Schnittbereich definieren
After customizing the parameters in the Job Editor accordingly, start the processing. The result can be opened, as usual, with a double click on the calculated job.
Schräger Schnitt in PointCab
Curved Section
With the Curved Section, irregularly curved objects can be unfolded easily straight from the point cloud, in order to analyze deviations. The results are true-to-scale 2D orthophotos, in which measurements of areas, length and height of curved structures can be taken.
Example “Semper Opera”, Dresden
Activate the “Curved Section” tool. Define the first point on the curved structure. With each further click, set another control point in the Top View, along the shape of the curved object and form the curved section. With a double click on the last control point end the creation of the curved section.
The control points can be subsequently moved in the Top View. Define the area of interest in the Top View. In one of the side views, the height of the section can be edited by moving the blue arrows up or down. The same can be achieved by using the numeric input in the Job Editor. The viewing direction for the curved section can be reversed by clicking the “Flip View” button.
In this example, the viewing direction points from outside to inside and the result is a planar orthophoto of the outer facade. Implicitly, the left and right sides of the unfolded surface are swapped. For more information on the settings in the Job Editor, such as resolution, intensity and color values, see the tutorial Processing Parameters. After adjusting all the parameters for the curved section, start the calculation by clicking the green arrow in the Job List.
The result can be open with a double click on the calculated job in the Job List or with a right-click on the element by selecting Open from the context menu.
SpaceWarp Processing Parameters
The Job Editor has the same structure for all three SpaceWarp tools. The individual categories are explained in more detail in this tutorial-chapter, using the example of the curved section.
Section Parameters
The section parameters can be adjusted in the Job Editor. The control points (i.e. the points that have been set to define the section) and the length of the section are automatically computed and given in the Section Parameters. In addition, the intersection area can be defined numerically here. The “Clipping” defines the used area of the point cloud to created the Section. It can either be adjusted graphically in the Standard Views, or its values can be changed in the clipping box. The red dotted line in the center of the section represents the projection surface. By default, the upper and lower bounds are set to a distance of 0.5 m. The values can be changed accordingly, in order to narrow the relevant area. The viewing direction of the section is indicated by the red arrow in the marked area. This can be reversed in the Section Parameters.
Processing
The settings for image resolution, reflectivity, color and scan radius can be adjusted in the Processing Parameters. These settings are already known from other PointCab tools. Using a color scale, the deviations from the projection plane are displayed in color in the PDF document. On the right side of the color map is an arrow-button, with which a drop-down menu can be opened. In this drop-down menu, you can set a discrete flow (hard gradient). The gaps between the colors can be set manually by moving the colored arrows. The colors can be adjusted individually. With a double click on the single arrows, a color palette appears. Fluous color arrows can be removed with the left mouse click.
The project name, the acquisition date, acquisition team, as well as additional annotations can be typed in the PDF Settings. The PDF report can be personalized by importing the company logo as well.
Scan positions
The scan positions that shall be used in the calculation can be easily and quickly chosen. There is the possibility to activate or deactivate entire clusters or individual scans.
CAD
In the CAD output options, the export unit, background color, image format, and projection of orthophotos can be customized.
File
In the File options the location of the PDF report and the created orthophotos can be changed, as well as the output format of the orthophotos. The DWG, DXF and DAE files are available as export formats.
Results of the SpaceWarp tools using the Cylindrical Section as example
PointCab generates the following results:
1. PDF Report
2. Orthophotos in CAD format (DWG, DXF or DAE)
In ths tutorial-chapter we will present these results using the example of the Cylindrical Section tool.
1. PDF Report
The PDF report is created in the Project_Results directory, folder Documentation:
PDF Report
The following information are documented in the PDF protocol:
a) cover sheet with project name, data collection timeframe and additional comments:
First page of the report
b) unfolded orthophoto
Second page of the report
c) deviations from the outer surface of the cylinder, depending on the view direction
Third page of the report
d) statistical evaluation of the deviations with histogram
Last page of the report
2. Orthophoto in CAD format (e.g. DWG format)
The orthophoto of the SpaceWarp tools is located in the Project_Results directory, folder Orthophotos.
Cylindrical Section in DWG Format
The DWG file can be now imported into the CAD application and further evaluated depending on the task.
DWG of the cylindrical section imported in Autodesk AutoCAD