FREQUENTLY ASKED QUESTIONS

 

Questions index

General questions

  1. How do I get SAL3D / 3DExpress?
  2. What is the best way to get started with SAL3D and 3DExpress?
  3. Which operating systems are supported?
  4. How do I get the documentation?
  5. Can I acquire only certain tools from SAL3D?
  6. Do I need a 3D camera for running SAL3D/3DExpress in my application?
  7. I am using a 3D camera, does it mean I get 3D information from the capture?

Licensing questions

  1. Does the license expires?
  2. What happens when the demo expires?
  3. If I use SAL3D or 3DExpress in different inspection stages, do I have to purchase as many licenses?

Peak Detector Tool questions

  1. How should the laser be seen in order to get the optimal results?

Metric Calibration Tool questions

  1. Is it necessary to always apply a metric calibration?
  2. I cannot calibrate. What can be failing?
  3. Is constant step between profiles required?
  4. How can I obtain an optimal calibration range map?
  5. How can I build my own calibration pattern?

Merger tool questions

  1. Which are the limitations of the Merger Tool?
  2. How can I obtain an optimal calibration RangeMap?
  3. What is the difference between the Merger Tool and the Integrator Tool?

Match3D tool questions

  1. How misaligned can the part and the model be?
  2. I can not align both clouds of points. What's wrong?

Geometric tool questions

Plane fitting

  1. Which are the Geometric Tool restrictions?
  2. Why do I get different results each time I use the Geometric tool?

CAD Import tool questions

  1. How does the CAD Import Tool work?
  2. Which resolution should I select?
  3. The CAD Import Tool is very slow. Is it normal?

Zmap (also Disparity map) questions

  1. Do I have to define the Zmap factors?
  2. How can I get a Zmap with a projection different than the Z plane?
  3. Can I create a Zmap of a COP subset?
 

General

 

1. How do I get SAL3D / 3DExpress?

A fully featured version of SAL3D or 3DExpress can be downloaded from our web-site, after registering in the download section. This version, after installation, includes all documentation in html format. The softwares have a free demo license which is valid during 90 days since the moment that they are first used. Afterwards, in order to be able to continue working with SAL3D or 3DExpress a license has to be purchased directly from AQsense or from one of our distributors.

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2. What is the best way to get started with SAL3D and 3DExpress?

You can start by registering in the download area, and get the latest fully featured release of SAL3D or 3DExpress. You have 90 days for evaluating all tools, implement them in your inspection system, etc.

SAL3D, along with the tool libraries, comes with some Range Maps, source code of example programs, precompiled binaries of those programs and a SAL3D Quick Start Guide. The whole documentation can be reviewed at SAL3D Documentation webpage. You can also check the SAL3D Video-tutorials webpage for some useful guides.

3DExpress documentation can also be reviewed at 3DExpress online documentation or in the html manual provided with the downloadable package. It may also be useful cheking the tutorials and video-tutorials webpages.

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3. Which operating systems are supported?

Any Windows version above Windows 2000 SP4 (Windows XP, Windows Vista, Windows 7, Windows 8...), both 32 and 64 bits versions. For GNU/Linux versions please forward your queries to This email address is being protected from spambots. You need JavaScript enabled to view it.

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4. How do I get the documentation?

Documentation is available from the program menu when installed. You can also check it in our web site at SAL3D online documentation or 3DExpress online documentation.

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5. Can I acquire only certain tools from SAL3D?

Yes, you might only need certain features, so you can buy the tools that are more convenient for you. SAL3D has been conceived as a flexible software, so more tools can be added afterwards if you require so.

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6. Do I need a 3D camera for running SAL3D/3DExpress in my application?

Both 3DExpress and SAL3D library can obtain data coming from a framegrabber or directly from a 2D or 3D sensor/camera. A full list of supported cameras and framegrabbers can be checked at the compatibility webpage.

Usually 3D cameras will provide faster results but, for laser triangulation applications where 3D cameras can not be used, they can be replaced by a 2D camera + Peak Detector (Like the COG included in 3DExpress or the SAL3D Peak detector Tool software)

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7. I am using a 3D camera, does it mean I get 3D information from the capture?

Some 3D sensors, like Time of Flight (ToF) cameras, directly returns calibrated 3D data (cloud of points). However, most of the 3D cameras (based on laser triangulation) do provide 3D information but not directly in metric units, just a depth value in pixels. In order to get calibrated 3D clouds of points for gathering metric measurements, the system must be calibrated first, for example, with the provided 3DExpress static Calibration or with the SAL3D Metric Calibration Tool

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Licensing

 

1. Does the license expire?

The license never expires once you have purchased it. The licenses of the free downloadable package expires 90 days after the libraries have been used for first time. The user can check the validity of the licenses using a web browser, looking at the URL: http://localhost:22350/

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2. What happens when the demo expires?

You will not be able to use 3DExpress or SAL3D tools until you acquire a license.

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3. If I use SAL3D or 3DExpress in different inspection stages, do I have to purchase as many licenses?

You need a license per machine (PC) where SAL3D/3DExpress is running. This concedes no restrictions in the number of cameras to be combined in an inspection stage or even the number of inspection stages along the production line (Beware of the speed and simultaneity constraints)

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Peak Detector Tool

 

1. How should the laser be seen in order to get the optimal results?

  • To get better results, it is better to avoid saturated pixels. The Peak detector gets worse results in case of more than 10-16 pixels saturated.
  • In order to get good subpixel, the laser should have more than 3-5 values over the threshold.
  • In case of more than one peak on a column, the peak detector tool automatically determines the most relevant one considering all the laser neighborhood (so, not only the max intensity of the laser).
  • The threshold should be set to distinguish between the laser and the background to assure that the maximum number of laser pixels are used to compute the peak.

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Metric Calibration Tool

 

1. Is it necessary to always apply a metric calibration?

No. The metric calibration is necessary only if we intend to gather metric measurements or register point clouds with Match 3D. If the 3D model is only going to be used in a comparative approach, metric calibration is not necessary.

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2. I cannot calibrate. What can be failing?

The calibration may fail if there are too many points not belonging to the calibration pattern. The solution is to either adapt the Region of Interest (ROI) of the camera to leave out those regions of the image, or to use the ROI functionality of SAL3D (or 3DExpress) when calibrating.

Problems on the pattern design or manufacturing may also lead to problems calibrating. Please refer to "How can I build my own calibration pattern?" for more information.

Other problems like a too noisy acquisition or the pattern not having a correct lineal moving may also cause the calibration to fail.

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3. Is constant step between profiles required?

Yes. In case of linear metric calibration this value must be constant, but it is not required to know it. In case of Static metric calibration, the user must know it in case he wants to use the calibration results to scan objects. It is not required for single metric profile reconstruction, like in Gap & Flush.

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4. How can I obtain an optimal calibration range map?

  • In case of linear pattern, it is recommended that the pattern is represented in, at least, 400 profiles. The accuracy on x axis increases with the number of profiles. In case you have less profiles, the calibration can fail.
  • In the static calibration, to ensure a good accuracy it is important to correctly align the pattern position with respects to the laser line.
  • The misorientation pattern indicates the misalignment in pixels between the pattern and the motion axis (y, and z axis respectively).
  • Enough points from the base plane in both sides must also be ensured.

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5. How can I build my own calibration pattern?

  • To design a new pattern, it is important to keep the ratio on each axis. It is not required to scale all axis on the same ratio.
  • Specular finishing must be avoided. So, sand blasting or white anodized are recommended.
  • You should check that the angles of the different planes allow a good acquisition. Base plane is also important on the calibration.

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Merger Tool

 

1. Which are the limitations of the Merger Tool?

The Merger Tool is only valid when two cameras observe the same region of a laser plane,  there is a constant step between profiles and the acquisition of both RangeMaps is synchronized.

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2. How can I obtain an optimal calibration RangeMap?

In addition to the Metric Calibration RangeMap recommendations, you should assure both base and auxiliary RangeMap have the same number of profiles

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3. What is the difference between the Merger Tool and the Integrator Tool?

They are absolutely different. The Merger Tool combines the RangeMaps obtained from two or more cameras looking the same laser line from different positions (observing the same field of view) in order to obtain a single RangeMap with less occlusions. On the other hand, the Integrator Tool combines Clouds of Points coming from different views (may be coming from the same camera) which share the same coordinates system (for example, being aligned with Match3D) to obtain a single mesh.

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Match3D Tool

 

1. How misaligned can the part and the model be?

  • The Match3D Tool requires the model and the part to be minimally aligned. If this is not the case, a prealignment or the coarse extension are two possible solutions.
  • The maximum rotation misalignment depends on the object shape, but typical values are between 10-15° on each axis (the rotation along the z axis is the most critical)
  • The maximum translation misalignment also depends on the object shape, but typical values are 1/5 of each dimension.
  • The quality factor gives an idea of the goodness of the alignment. It is not 100% robust, specially when model and part size are quite different. However, it can be used to check if there is an alignment problem.

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2. I can not align both clouds of points. What's wrong?

There are several possible reasons of misalignment:

  • Not enough valid points:
    • The Model or the Part objects do not have enough shape information (f.e. when trying to align two planes)
    • Model or part has not positive normals. Match3D only uses points with positive normals, so if COP axis is a left-handed coordinate system, all normals are pointing from outside to inside, so, they are not used on the minimization. User can display the COPs in Points mode with Full Lighting illumination to see which object faces has positive normals. This can be solved by saving the model or part having not positive normals with the option "cop reverse".
    • Model and Part are located one far from the other. User can use the option Match->Set Initial Movement or use Shift + Mouse controls to prealign both parts.
  • Both parts has not enough common information: In general, in case of good prealignment good results with around 50% of overlapping
  • Unstable shapes: Simple shapes have some unstable movement axis. For example, a single plane has two unstable translation and one unstable rotation axis, and sphere has 3 unstable rotation axis, and a cylinder one unstable rotation and one unstable translation axis. In that case, it is not possible to align with accuracy in these axis.
  • Bad triangulated COP: SAL3D tools uses the COP cells neighbors to triangulate the COP object. In case the COP is badly populated, object will be bad triangulated, affecting the alignment. To assure a good triangulation, user can display the object in solid mode.
  • Due to some calibration problems, objects have not the same dimensions...

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Geometric Tool

Plane fitting

1. Which are the Geometric Tool restrictions?

The Geometric Tool requires the main part of the COP to be a flat area. The "expectedInliersRatio" gives to the algorithm an initial idea of the Percentage of points belonging to the plane.

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2. Why do I get different results each time I use the Geometric tool?

The robust version of the plane fitting tool is probabilistic so, different tests can return different results.

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CAD Import Tool

 

1. How does the CAD Import Tool work?

The CAD Import tool creates a virtual scanning of the CAD depending on the window orientation. For more information on how it works you can watch the CAD Import Tool Video-tutorial

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2. Which resolution should I select?

The user has to select the COP resolution to make it similar to the scanned parts.

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3. The CAD Import Tool is very slow. Is it normal?

Yes, CAD Import is extremely slow for STL files. However, we think that for small STL files (with not too much triangles) it is not a big problem because STL files must be imported just once. For big STL files please contact us at This email address is being protected from spambots. You need JavaScript enabled to view it.

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Zmap (also Disparity map)

 

1. Do I have to define the Zmap factors?

Yes, Zmap factors should be defined by the user. The default parameters get the COP size and the COP range in X and Y (using only valid points). If interested, you should compute the zmap factors that assure the same ratio pixel/metric in both axis (x and y)

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2. How can I get a Zmap with a projection different than the Z plane?

In order to have ZMap from another projection you can reorientate the COP before the ZMap projection.

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3. Can I create a Zmap of a COP subset?

Yes, you can create ZMaps of a COP subset by modifying the ZMapfactors related to the X and Y range.

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