3D scanner

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3D scanners

We have 2 types of 3D scanners in the Virtual Reality lab. The David-laser scanner ([1]) is a simple one. You can use a laser by hand, to shine over the model. Use this one if can’t use the other one. The other scanner is from NextEngine [2] this one is more professional and you can make high quality 3D models with it.


Building a set

Building a set is actually as simple as unpacking the box and to connect everything. The only thing to be considered is the size of the object will be scanned.

Example.png

Example of a set from above The disk is close to the scanner, close enough to use the 'macro' mode when scanning.

Scanning an object

Scanwindow.png

The scan window, for starting a new scan The scan window shows two things, the image of the camera (colorless), and the settings for the scan. In the image on the right, a square can made with the mouse, everything outside that area is not scanned. Even after turning the object this same imaginary plane remains in operation. So if you want to scan an item that is not equally wide, and you want to cut the edges (for things that don’t need to be scanned), it is wise to turn the object with the button labeled 'Turn' at top center and see if it stays within the plane.

On the top in the yellow textbox, you can enter the name of the scan you are going to make, than it is easier to find later 'Scan_01 "etc. Once you are making multiple scans of the same model, and you don’t close the current program, the program completes the name itself with "_01" etc to keep everything together.

Settings.png

These are all possible settings for a scan. Top next to "Positioning" you can choose what type of scan you want to do. • A 360 ° scan, all the way around. • A bracket scan, 3 scans where the middle is the current image. • A single scan, a single scan from the current camera image. The number of divisions for each scan type is different. Where a 360 ° scan stands for the total number of scans that are made. The bracket scan gives the angle between the three scans. A higher number of divisions is a lower angle. By single scans divisions is not used. The number Points / IN.² " is the number of points per inch. The higher this numbers the finer the scan. On the other hand of course such a single scan takes longer when there has to be precisely scanned. "Target" represents the color of the object. This choice improves the speed of scanning and you can experiment with it, as the results are disappointing this option can help. The "Range" indicates how far the object is away from the scanner, and decides how far the camera is zoomed in and what set of lasers is used. For large objects when not fit in macro picture, it is best to have the wide range to choose. At the bottom there are the estimated time and used memory. The time is fairly accurate, and it shows your used intern memory and the size of the saved scan. If the maximum quality scan is selected, don’t be surprised if the scan is a few gigabytes. Once you are satisfied with the settings, you only press the start button and sit back. During the scan you could cut in the scan. But if you cut after the scan is complete you can do it once.

Clipping a scan

Clipping.png

Example of a scan that needs to be clipped . After you have finished scanning an object, there may be something extra scanned like the gripper arm, or the bottom plate. This can be removed by the 'Trim' button at the top picture again. Then there are the following buttons on the screen after a backup is made.

Toolbar.png

With these buttons you can select and remove the wrong parts. Everything what is marked red will be removed. Be careful with this, because everything you select is also selected on the other side of the model. You can undo this by clicking on deselect and erase from a different angle. After you have selected everything that can be removed, press 'Trim' and it is removed in all scans. So you do not to cut the object on every angle.

Merge multiple scans

Once you are satisfied with the results of a scan, you scan the same object again, at a different angle. For example, to take the top and bottom of the model. When done, these scans are merged. This is done with the button "Align" top center.

Allignscreen.png

‘Align’ screen with 4 pins Aligning the image is divided into two parts, one for each scan you are going to align. The scan in the lower left in,the green box, is dragged on the left screen, and the other is simply clicked. Once you have two good scans, you can start placing pins at same points of the model. At least 3 pins are placed. A trick for objects that have no sharp edges is to place marks on them before the scanning. The pins can be easily placed, drag them from the top right of screen on the model and place a pin with the same color on the same position of the other model. After enough pins are placed, you can choose the precision with the slider at the top picture. Then you can click on "Align" button to start the alignment. After this is done you can still improve the precision by the 'Refine' button and the scans to align more precisely.

To improve a model

After multiple scans are combined there are still a few things to do before the real model can be exported. Namely the tightness of a model, and to improve imperfections. Under the button 'Fuse' you can make the model tightness and also simplify it. This is necessary if you have scanned on the highest quality because then there are already almost 2 million polygons in the model. That is obviously too much, certainly if you want to use the model in a realtime 3D environment. You can choose to merge with the slider "Simplify", put this number on 0.0500 that is a pretty good value to simplify the model, but of course this also depends on personal preference and purpose of the model. Under the button 'Polish', there are three ways to improve a model: • Fill  Filling Holes • Buff  Smooth sharp edge and wrong textures. • Simplify  Downsize polygons in a particular place on the model to save memory and still keep detailed parts of the model.

To export a scan

Exporttoolbar.png

Export scan possibilities Once you have completed a scan, you can click "Output" button to start exporting. Here are several options: • OBJ Exporting to a. obj file, which many 3D programs can be read • STL  Exporting to a. stl file, which is widely used by CAD software • 3D Print Direct to a 3D printer • IGES  Can only in the next version of Next Engine, for a more direct CAD output • STEP Can only in the next version of Next Engine, for a more direct CAD output • Rapid Works Forward to rapid Works (Should be installed) • SolidWorks Forward to SolidWorks (Should be installed) • More  here you can still choose from the following formats: • 3D engine next file (*. scn) • portable 3D engine next file (*. nzip) • file PLY (*. ply) • OBJ file (*. obj) • STL file (*. stl) • VRML file (*. WRL) • file XYZ (*. xyz) • IGES file (* igs / *. iges) (CAD software from Next Engine installed) • STEP file (*. step / *. stp) (CAD software from Next Engine installed)


Limitations on objects

The next engine software handles areas that are difficult / bad to scan, can be quite simple: They are skipped! To prevent this you should look at the following points • An object shouldn’t be so transparent that the laser line is almost invisible on the model. • An object shouldn’t reflect so much that the laser line is no longer visible • An object shouldn’t have deep grooves that aren’t visible for the camera. • An object shouldn’t absorb so much light that the laser line is not reflected.

If you want a transparent or reflective object to scan, you can cover the object with baby powder or flour. In the next enginebox there is a pen / brush filled with powder. This is special for highly reflective or very dark models. It is recommended the make the model white with this brush. The textures have to be scanned later separately.

Control of the 3D window

3Dwindow.png

To control the camera in the 3D window you can use the mouse.

• Zoom in / out

       o	scroll wheel
       o	Right mouse button and drag up or down

• Rotate

       o       left mouse button and drag
       o	Middle mouse button and drag

• Move

       o	Both mousebuttons and drag

On the bottom of the screen you see the different scans and the merged scans. These are clickable to show on the big screen. If you drag more scans in the green box you see them together.

Bottom right you can change the display of four choices:

• Color

       o	Model with texture on it

• Shaded

       o	Model without texture

• Mesh

       o	Wireframe display

• Points

       o	Display of the points of the model