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Large/huge objects processing

This is the second article dedicated to the scanning and post-processing of large and huge objects. While some scanning tips and tricks were provided in this article, below we will focus on post-processing.

Setup

1.1. Choosing optimal hardware

Some examples of suitable hardware configurations can be found here.

An Intel i7 or i9 CPU is highly recommended. The more cores and the more power per core - the better.

RAM requirements:

  • The amount of required RAM will greatly depend on the size of your project. While Artec Studio is able to make use of the Windows pagefile in case the RAM overflows; this will cause a considerable slowdown in processing speed.
  • The rule of thumb for successful processing: you will require 3 times more RAM than the size of your raw data.
  • There is no upper limit, so feel free to install any amount of RAM that you need for your project.

An SSD drive is highly recommended, as it provides faster project saving times and a faster interaction with the Windows pagefile.

 

1.2. Windows pagefile

Artec Studio will use the Windows pagefile only when there is insufficient RAM to load and process all the selected raw data. We recommend adjusting the pagefile size before beginning with the post-processing.

If your PC is equipped with multiple disks, one of them an SSD, make sure that the Windows pagefile is located on the SSD. While an SSD is slower than RAM memory, it is still significantly faster than an HDD.
Do note that the SSD needs to be large enough to fit the pagefile. Otherwise, it too will eventually overflow, which may cause freeze-ups and crashes of the PC and/or Artec Studio.

The sequence of how to configure the pagefile is shown in the picture below (we recommend setting the pagefile to 100 GB or more).

Note: Artec Studio may show that it currently uses more RAM than the total RAM amount installed in your PC. This indicates that Artec Studio is using both the RAM memory and the Windows pagefile.

Preparation

2.1. "Unloaded scans" mode

If you would like to open a very large project on your PC, it is more efficient to use the option Open project (unloaded scans).

This option will open only the project structure, while all the data will remain unloaded from the 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 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 a large object, you will have a project with quite a lot of data. 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 the 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 the scanning process, rename your raw scans now. It helps a lot to keep the project organized.

Have a look at the project of a 5-meter tall statue below. The corresponding scans are named as legs1, legs2, legs..N, body1, body2, body..N, head1, head2, head..N, 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 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 the "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 the available RAM amount and you can not load all raw scans into RAM at the same time.

Global registration (individual/selective):

  1. Open project in "unloaded scans" mode.
  2. Select several scans in the project, load them into RAM. Continue loading scans until about 75% of RAM is being used (it is shown in the left-bottom part of the Artec Studio screen).
  3. Perform the 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 the 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 a 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 the "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 a quick preview to play with different settings and find an 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 in 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 performing fusions 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.

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