RUG/Pennsylvania/State College/3D scanning

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NextEngine 3D Scanner

Current Progress

Penn State RUG is currently using the NextEngine 3D scanner to replicate and print objects. The initial scanning process is relatively simple, but aligning point data and creating a water tight model is a tedious task. The NextEngine ScanStudio software has successfully produced printable files and other software exists that makes turning the scan into a clean printable model. Penn State RUG currently uses Netfabb and Blender to clean, touch-up and ready a scanned model for printing.

When to scan

Scanning is good for replicating objects that are already made. The Scanner used by Penn State RUG is the NextEngine laser scanner. There are some negatives to the laser scanner that need to be taken into consideration when choosing if the object will scan well.

Surface Finish

Laser scanners have problems scanning objects that have a shiny surface since the light is reflected. Laser scanners also have a problem scanning objects that are dark in color, since most of the light is absorbed. One way to correct this is to apply talcum power to surface using the brush supplied with the NextEngine. If the powder is not stick apply hair spray to the model before brushing with talcum powder. If powder does not work then a light colored matte paint can be applied to surface of the model. Be careful to not apply too much paint so that the object's features are obscured.

Geometry

Laser scanners will ignore features that are not visible from the surface, like internal hollow shapes. They also have issues with undercut angles, since there is no way for the lasers or camera the reach behind the face of the object. To reach hidden faces try repositioning the model and scanning again.

How to scan objects

ScanStudio HD interface
ScanStudio HD Scan Mode

Place your object on the stand in front of the scanner. Using the image on the right side of the scan mode, center your part in the frame.

1. Choose Positioning of scan, there are three options to choose from.

360 scan rotates the object 360 degrees and takes scans from many different positions.

Bracket takes three scans separated by the user inputted angle.

Single scan takes a single digital image in it's current position.

2. Choose the number of divisions. The division changes the angle between each scan. In 360 scans, the number of divisions is the number of scans it will take to complete the full circle. If 4 divisions are chosen the angle between each scan will be 90 degrees.

For a bracket scan the division changes the angle between each scan. To find the angle between each scan divide the division number from 360. The divisions slider is not used for single scans.

3. Choose the density of each scan. The higher the density the more data points per square inch. A higher number of data points that are taken means more detail but also a larger file size and longer scan time.

Optional: Choose your target. This is used to tell the scanner if the piece is a light, neutral or dark color.

4. Choose the range of the scan. There are two main modes used by Penn State RUG, macro and wide. The optimal distance from the object to the scanner for macro is 6.5 inches and 17 inches for wide. Once you have adjusted the distance you may need to recenter your part in the frame on the right side of the computer screen.

At the bottom of the scan window there are bars that will show the time and memory estimate for the scan.


Aligning, Trimming and Fusing scans

To create a complete 3 dimensional image, you will probably need to run several different scans with your object positioned at different angles. The example below shows a model of a person’s head made from a 360 degree scan with the model positioned upright plus a single scan of the top of the model’s head.

"Head model before being aligned

Aligning

Head Model after being aligned

Aligning multiple scans will help to position them and line them up so they can be fused into one model.

1. To start aligning you scans click the align button at the top of the ScanStudio main page. A number of dots will appear on the screen.

2. To align the scans start by placing the red dot on either of the images. Then place the other red dot on in same spot on the other image. The better the precision the better the final product will be, so pick a prominent feature.

Note: It may be help full to mark the object before scanning for easier alignment.

3. Continue to place the blue and yellow dots just like the red dot in step 2.

Note: Three dots is the minimum needed to align the scan but more dots can help to provide better precision

4. When all the dots are placed hit the align button at the top of the window and Scanstudio will align do the rest of the work.

Trimming

Head model before being trimmed
Head model after being trimmed

Trimming the model will allow for removal of any extra data that is not needed. There are six main tools that can be used to trim the model. These can be seen at the top of the trim page.

Pointer

The pointer can be used to move your model without fear of accidentally selecting necessary data and deleting it from your model

Circle

The circle allows for the a circular patch of data to be selected for removal. To use it click and hold the left mouse button and highlight the data that needs to be removed.

Square

This square is the same as the circle but selects a square patch of data.

Square line selector

The tool allows you to select a large area for removal. It works by creating a box around the data that is going to be removed. Click on one part and move the mouse the other side, creating a square with you two data points being the on a diagonal from each other.

Lasso

The lasso allows you to select large areas of data to be removed. Clicking on a spot on the screen allows you to create a line by connecting a group of lines together. All the data points enclosed will be selected for removal.

All

Selecting all will select all data for removal

Process

1. To start trimming your model click the trim button at the top of the ScanStudio main page

2. Choose your trimming tool from the tabs at the top of the page.

3. Hold down the right click button and highlight the data that needs to be erased.

Warning: Be Careful to select only data that needs to be erased

Note: You can choose to either select data or deselect it by choosing the plus of minus button

4. Once all data is selected click the trim button at the top and let the computer remove those data points.

Fusing

Head Model after being aligned

Fusing the model will turn a family of scans into a watertight model that can be printed

To fuse the group of scans together, click the fuse button at the top of the main ScanStudio page. Choose the level of tolerance for the scan and click fuse.


Making Scans printable (incomplete)

To make a watertight model printable there are different methods that can be used. The three main methods used by Penn State RUG are ScanStudio Polish Tools, Netfabb, and Blender.

ScanStudio Polish Tools

There are three main tools that are included in the ScanStudio software

Fill

The fill tool allows for holes in the finished model to be fix.

Buff

The buff tool smooths the surface of the scan.

Simplify

The Simplify tool will simplify the mesh and lower the total file size. It can be used to lower the number of data points on areas with constant geometry, like smooth and flat surface.

Netfabb

Netfabb is currently used to make the bottom of the print flat for easier printing. It is also used to fix error that can arise during conversion to .STL that causes slic3r to slice it incorrectly.

Making Flat Bottom

Fixing STL

Blender

Blender can be used to add details that were lost or remove surface flaws that appeared during the scan.

Extras

Pictures

Statue of Poseidon Scan of statue of Poseidon Printed Model of Poseidon statue Duster pen included with Nextengine Scanner

Links