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Large/huge objects processing

This is the second article dedicated to efficient scanning and post-processing of the large and huge objects. After we revealed some scanning tips and tricks in this article, let's check post-processing of huge objects as well.

Setup

1.1. Choosing optimal hardware

We have posted a sample hardware configuration here, it was used it for post-processing large Napoleon statue.

You will need Intel i7 processor; the more cores and more powerful every core is - the better.

Speaking about RAM requirements:

  • Artec Studio will operate and post-process your data even if you have a shortage of RAM on your PC, but for comfort post-processing of huge object we recommend minimum 32 Gb of RAM.
  • General formula for comfort processing: 3 times more RAM than the size of your raw data is.
  • Our clients usually use around 64 Gb RAM for post-processing huge objects.
  • There is no upper limitation, so feel free to install any amount of RAM that you need for your project.

Also we highly recommend using SSD hard drive, as it provides faster project saving, faster interaction with Windows pagefile, etc.

 

1.2. Windows pagefile

Artec Studio will use Windows pagefile only if there is not enough of RAM to load and process all raw data at the same time. So we recommend to adjust the pagefile size before you start post-processing.

If you use SSD, be sure to select the location of Windows pagefile on this drive.

The sequence is shown on the picture below, we recommend setting 100 Gb and more.

Note: Artec Studio may show that it currently uses more RAM than total RAM amount installed at your PC. Don’t be alarmed, it indicates that Artec Studio is using both RAM and Windows pagefile.

Preparation

2.1. "Unloaded scans" mode

If you would like to open project of a big size on your PC, it is more efficient to use option Open project (unloaded scan).

This option will open only the project structure while all data is unloaded from RAM.

 

2.2. Unloading/loading data

When you manipulate large datasets and do not need to keep them all in RAM at the same time, you can unload such raw scans or 3D models from memory (via right-click in "Workspace").

If the data is unloaded, then the main advantage is that it does not occupy RAM, but it is still stored on the hard drive, still remains in your project and is accessible any time.

 

2.3. Quick selection of scans in "Workspace"

These shortcuts will be helpful for quick switching between large datasets of raw scans in "Workspace":

  • CTRL + LMB: Select one scan and leave others non-selected
  • Ctrl + A: Select all scans/fusions or frames
  • Ctrl + D: Deselect all scans/fusions
  • Ctrl + Alt + A: Invert selection of scans/fusions

 

2.4. Primary analysis of the project

After you finish 3D scanning of a large object, you will have a project with quite a lot of data inside. For example, non-experienced users tend to capture more data than is actually needed or to return to the same place on an object several times.

Now it is time to analyze raw scans more precisely and to decide which ones you will use in post-processing.

  • Detect duplicated data and remove it or mark it as such by renaming the scan and unloading it.
  • Use eraser to remove unwanted parts or parts of the scene that you do not need. It will speed up registration algorithms.
  • In case you do not use prefixes in scanning process, rename your raw scans now. It helps a lot to keep the project organized.

Have a look at the project 5-meter statue below. The corresponding scans are marked as legs1, legs2, legsN, body1, body2, bodyN, head1, head2, headN, etc. Duplicate scans are unloaded from RAM:

Important note: Before you start to delete any raw scans from your Artec Studio project, it is highly recommended to back up this project.

 

Post-processing

3.1. Preset with algorithms parameters

Be sure to select correct preset in File --> Settings --> Scan --> Current scanner type:

This preset affects all post-processing parameters of all algorithms, so it is important to set it correctly before you start post-processing:

  • M-type scanner: Eva / Eva Lite / MH / MHT / M
  • S-type Spider scanner: Spider / Space Spider

 

3.2. Special registration settings

This method is applicable if your object has sufficient geometrical features:

Switch fine and global registration to "Geometry" mode:

How it works: Artec Studio will analyze only one parameter (Geometry) instead of two parameters (Geometry and Texture) for every frame in your raw scans.

Result: Post-processing speed of registration algorithms will increase 4-10 times, exact time depends on the size of raw scans.

When not to use: If you have any kind of pattern on the flat areas of your scanned object and you would like to use this pattern for registration, then "Geometry only" method is not applicable.

 

3.3. Solving "Not enough RAM" cases

The workflow described below is applicable for cases when your project size is bigger than available RAM amount and you can not load all raw scans into RAM at the same time.

Fine serial registration:

  1. Open project in "unloaded scans" mode.
  2. Select several scans in project, load them into RAM. Continue loading scans until about 75% of RAM is being used (it is shown in left-bottom part of Artec Studio screen).
  3. Perform fine serial registration.
  4. Unload these scans from memory.
  5. Load next portion of scans, perform fine registration for them and so on.

Align:

  1. Select several scans in project, load them into RAM. Continue loading scans until about 75% of RAM is being used.
  2. Perform align for these scans, apply the changes and save the project.
  3. Unload everything except a couple of already aligned scans.
  4. Load new portion of raw scans for the next align session until about 75% of RAM is being used.
  5. Align them with already aligned scans from p.3. Save the changes and save the project.
  6. Continue from p.3.

Global registration:

A little known fact is that you can select unloaded scans for registration and Artec Studio will dynamically load them.

  1. You can start even with all scans unloaded from RAM, just make sure they are aligned already.
  2. Choose "Geometry" parameter in properties of global registration (if applicable; see above).
  3. Select all scans you need and launch global registration for them.

Fusion:

  1. Smooth fusion isn’t effective for large objects.
  2. Use Fast fusion as quick preview to play with different settings and find optimal resolution parameter.
  3. Resolution for large objects is bigger than default one and usually starts from 3-4 mm (for both Sharp and Fast fusion).
  4. If the object is 3 meters length or bigger, run fusion for several parts separately, then align such fusions together and run fusion of fusions to combine them. We do not usually recommend to run fusion of fusions, but it is acceptable for large/huge objects.

Mesh simplification:

Two fastest methods of mesh simplification to use are Fast mesh simplification (separate button) and "Remesh" option inside regular Mesh simplification algorithm.

 

Interested to check customer's tips and tricks while scanning huge objects? Check this case study: Napoleon monument scanned with Artec Eva 

 

We are here to help! If you have any questions or issues, please do not hesitate to contact our team by emailing support@artec-group.com or by clicking on "Ask Support" button on the upper part of the screen. We will always be happy to assist you and will get back to you as soon as we can.