14 Best Practices in Scan to BIM

by Jun 27, 2018BIM0 comments

Scan to BIM

S can to BIM or Point Cloud to BIM is the most accurate method to create As-Built BIM Models of any existing Buildings or Interior spaces. Not all Laser Scans are equal. A lot of times there are Blind Spots or missing data. Incomplete low-quality, low-density Black & White can be very difficult to Model accurately and can sometimes take a long time to model as the modeler needs to decipher and interpret missing or low-resolution Point Cloud Data. This article describes best practices you should follow to would help you get the best results

Scan to BIM Process

let us first understand the Process. Scan to BIM is essentially composed to three stages:

  • On-Site Scanning
  • Registering & Combining Raw Scans
  • BIM Modeling
    1. On-Site Laser Scanning using Laser ScanningCameraLaser Scanning is done on site using special cameras. This could be done in Black & White or Color. Color Scans are clearer and are relatively easier to Model accurately.
    2. Registering Raw Laser ScansRaw Laser Scans need to be processed. There are typically multiple scans for a large facility. These multiple scans need to be combined using software such as Autodesk Recap Pro.
    3. Converting Registered Laser Scans to BIMAfter processing Raw Laser Scans, they can be imported in BIM enabled software such as Autodesk Revit. Be sure, you understand the Scope of work and LOD required for deliverables

On-Site Scans

This is the starting point of your Project

  1. Define Scope of Work and level of DetailIt is critical that the scope of Wok is clearly and precisely defined for the Project.
  2. Define the Scanning Process and methodologyDefine methodology to be adopted before sending in field staff.
  3. Use High-Quality ScannersUse High-Quality Scanners can produce point-cloud density needed for the specifications and LOD needed. High-Density Color Point Cloud Data is critical for high accuracy. Scan to BIM Model and can help you save. This is because of clarity in data, helps reduce Modeling time and as a result lower cost.
  4. Plan your scanning Process.

    Identify Camera Positions and ensure Circles of each Camera overlap

  5. Support Point Cloud Data with Photographs and 360 Walkthroughs.This helps modelers understand space and elements that are unclear in Point Cloud
  6. Field Notes can help in accuracy.Not all information is clear in Scan data, Field Notes take a higher priority over Point Cloud and result in a more accurate BIM Model

Registration

Each Project will have multiple scans in order to scan a Building or an Interior space. Autodesk Recap Pro can take this raw data and automatically register the raw data.

      1. Number the scans sequentially.Number raw scans sequentially. This helps in aligning scans properly.

Modeling

This is the final step in Scan to BIM process. Now that you have Scan data. Import it into Revit. The following steps will be helpful in accurately modeling from Point Cloud.

    1. Check out Scope of work and LODVery often BIM Model produced does not match the required Scope or level of Detail that is required for your BIM Model. It is therefore important that every member of your team clearly understands this.
    2. Establish Survey pointIdentify and establish Survey Points if available in your scan Data and use them to establish these in your BIM Model
    3. Pin your Point-CloudOnce your Point Cloud is in Revit, Pin it so that it does not move by mistake
    4. Setup Levels.When you import Point Cloud, you will need to establish levels. Your level 1 Plan may not show anything. Use 3D Elevation Views to establish levels.
    5. Adjust View Depths.Without adjusting View Depths, you may see a huge amount of Points and these may become confusing
    6. Cross check your modelCross check your model against Photographs Field Notes and 360 Walkthrough.
    7. Use NavisworksIf 360 Walkthrough is unavailable, use Navisworks walkthrough

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