Clash Detection in Navisworks and Revizto

Сomparison was conducted based on September 2023 functionality for both softwares.

Clash detection

The construction industry as a whole has a rather long-running reputation of being incredibly complex and sophisticated, while also being one of the slowest industries in the world when it comes to changes and innovation. A large part of this is because every single construction project is an incredibly complex undertaking with unique design & field constraints, evolving standards & building codes, and hundreds of team members with varying levels of skills & experience coming together to create a building which typically has never been built before.

The sheer number of people involved is just one of the many challenges  – because a lot of teams are specialized to focus  on a specific scope of work for the project, and only share it with the rest when it is complete or reaches a milestone. This is often referred to as working in a silo or compartmentalization. It can be seen in architecture, structural, mechanical, electrical, plumbing, fire protection, and many other scopes of work, and the overall project complexity increases exponentially depending on contract type, number of design teams involved, complexity of building types, evolving building codes & technology, etc. This all needs to be factored into consideration before undertaking any building project.

The fact that every construction project has both time and budget constraints with team members of varying levels of experience & skills also means that there are a lot of moving parts and stakeholders involved which all need  to reach a certain level of cooperation & understanding for the project to be successful.  However, coordinating these moving parts during installation is extremely time-consuming and inefficient. Projects must increase operational efficiency & predictability in order to be successful & profitable in today’s competitive marketplace. This is where clash detection can be useful.

Clash detection is a tool that is used to determine conflicts between (2) or more separate sets of geometry (ie. Struct Steel vs mechanical or electrical parts). It automates the process of discovering where 3D elements are in conflict with each other through the use of programming a script that includes various rules & constraints applied to return desired results.

Clash detection is also an integral part of coordination using Building Information Modeling (BIM) – another popular topic in the construction industry that puts a lot of emphasis on boosting collaboration and cooperation early on during the design & preconstruction phase by offering a single source of truth in a centralized cloud based platform where digital models can be combined, viewed, coordinated, and tasks assigned to each team member in order to coordinate & detail a project virtually prior to anything being installed on site.

In addition to clash detection as a value added service, it is becoming more common for builders to partner & assist designers much earlier using project delivery methods such as design build, design assist, or integrated project delivery (IPD) than the traditional design-bid-build approach. This is due to the main benefits gained from providing insight & valuable constructability input which allow disciplines to coordinate holistically much earlier in the design process rather than after the project has been finalized and presented to a builder. The main reason is due to the fact that it is much easier & quicker to alter the design during the early design phases than after all the contract drawings & details have been completed & permitted by the city having jurisdiction. This is demonstrated below in what is known as the MacLeamy curve:

The main goal of clash detection is to identify locations where specific model elements conflict and notify the primary team members in order to resolve it digitally before it becomes a problem during construction. This has become more common especially as project budgets & schedules have tightened and as more companies are looking for more efficient ways to identify risk & utilize prefabricated assemblies to reduce costs & rework. This requires the work to be fully coordinated prior to releasing any material for fabrication or installation. The existence of clash detection in the context of advanced 3D parametric modeling (often referred to as BIM) allows for model conflicts to be either greatly reduced or completely eliminated.

However, it is important to note that clash detection by itself can not distinguish what is missing or incomplete in the design or contract documents. It simply is an algorithmic tool designed to detect where geometry is in conflict with each other in the 3D space. It still requires those who are experienced in design & construction to collaborate in order to ensure complex design issues are buildable and meet the necessary design intent, code requirements, cost, schedule, etc. to fulfill the contract.

Types of clashes between models

In an industry as complex as construction, it is not particularly surprising to learn that there are multiple types of clashes that could happen between two or more models. Below you’ll find a list of three different clash types, each with its own specific features and use cases:

Hard clash

Hard clash is what most people would imagine when hearing the word “clash” – it is the event of two components or objects being located in the same space within one model. Some of the more common examples of hard clashes are plumbing conflicting with air ducts, pipes crossing steel beams, and so on.

Tolerance

Clash tolerance allows for tolerance to be set  – setting a specific distance which defines what clashes are detected as valid and what clashes can be ignored that are equal to or less than the specified tolerance. For example, if I have sprinkler lines conflicting with the insulation on the mechanical ducts, I may use a ½”tolerance since there is wiggle room within the insulation of the duct so any sprinklers that conflict ½” or less with the mech duct will not be counted as a clash.

Clearance

Clearances are somewhat less obvious, they represent indirect interference between the two objects when each object has its own spatial or geometric requirements. . The MEP industry is one of the most common sources of required clearances , because of the access requirements that are required by the building code or manufacturer.

There are multiple clearance clash types that exist in construction projects, including:

• Regular clearance
• Top-Bottom clearance
• Horizontal-Vertical clearance

Clearance clashes may not seem particularly important at first, but they can create problems  such as access for maintenance, general safety concerns, code requirements, and so on.

Clash detection in Navisworks

Autodesk Navisworks Manage is a model aggregating software that was created with the primary goal of federating models & improving BIM coordination. It helps the entire AEC industry with coordination and ability to compress a large number & variety of different model file types. It also supports a variety of different  software plugins, can be used for simulating schedules, model based estimating, and more.

One of the most prominent features of Navisworks is clash detection – the ability to identify and resolve conflicts using a virtual model of the project before construction.

Navisworks can run clash detection against multiple files or search sets, group clashes using multiple parameters (although the process can only be performed through the use of additional plugins or subscriptions purchased separately), apply different color schemes, create view points that can be shared with the team through the use of various plugins. Navisworks offers advantages such as:

• Improved  ability to view & coordinate a large number of models
• Reduced number of modeling errors and trade conflicts
• Improved design accuracy & coordination of disciplines
• Ability to load NWD files into model authoring software & other 3rd party model viewers
• Ability to integrate & sync with the Autodesk Construction cloud >Model coordinate module

A lot of different information is available when it comes to the capabilities of Navisworks in terms of clash detection. You’ll find one example of that below.

Clash detection in Revizto

Revizto is a cloud-based visual collaboration software for the AEC industry that offers vast communication capabilities inside of a project in the context of a convenient 2D or 3D environment. Revizto unifies a large variety of data such as 3D models, 2D drawings & a built in issue tracker that georeferences all issues to it’s known xyz location when viewing an issue in either 2D or 3D. Built on the Unity gaming engine, models of any size or complexity are compressed to a fraction of their original size making it easy & reliable to use on any device by all team members.

Clash detection is one of the most robust features of Revizto, offering plenty of tools that can automate & provide results that are refined & relevant to the trades responsible for the work. Revizto allows for all issues to be tracked in real time & filtered based on what information needs to be communicated and by whom. Reports & dashboarding of how the project is performing is provided in real time keeping team members accountable to maintaining quality of their work & meeting schedule deliverables.

Not only is Revizto capable of working with its own data and data imported from other clash detection/BIM solutions – it also goes a step further with its offering of a fully integrated clash automation feature. Clash Automation is an integrated solution that combines clash detection, auto grouping, auto sectioning, and auto assigning clashes to the correct party in a single environment that can offer a number of advantages, including:

• Grouping clashes as soon as they are detected
• Filtering results for specific stakeholders to simplify and speed up the feedback process
• Multiple clash tests can be opened by different users & run  at the same time based on permission settings given, improving productivity & eliminating the need for only VDC specialists to perform it.
• Allow all project stakeholders access to view clashes & issues which eliminate information from being bottlenecked to only a handful of VDC specialists.

Revizto vs Navisworks in clash detection

The easiest way to determine which product offers the best & most comprehensive solution – Navisworks or Revizto – would be to compare the two products directly. Since both of these products are unique in the way they operate and have multiple tools, this comparison would be focusing on comparing a single feature – clash detection.

In order to keep the comparison organized & easier to follow, we are going to be splitting it into categories – describing the  advantages and disadvantages of each.  The categories reviewed between each product are as follows:

1. Tool optimization
2. Clash set up
3. Sorting & filtering
4. Visualization
5. Reporting & issue tracking
6. User interface
7. Interoperability
8. Access & security

Tool optimization

Description	Revizto	Navisworks
Ability to group or filter clashes based on user defined zones allows  users to prioritize coordination efforts based on different zone locations. Zones can also be used as a method of filtering clashes based on what zone clashes are located in or based on the priority of the zones being clashed.
Auto grouping by system classification, level, proximity, zone, etc reduces the time required to review & sort through thousands of individual clashes Both Revizto and Navisworks are capable of grouping clashes for convenience’s sake, but Navisworks needs an additional plug-in for that, while it is a built-in feature of Revit (See comparison of the same clash test performed (Struct steel vs plumbing – Revizto clash test example, Navisworks clash test example)
Can handle a large number of complex models & many different file types commonly used in the industry
Ability to load & compress data quickly
Ability to load & import reality capture & point cloud data
Ability to run clash detection against point clouds
Ability to view clashes on 2D sheets. All clashes recognize the x,y,z coordinate location inside Revizto so the pin locations show up in 2D or 3D space
Ability to sync clashes to issue tracker to make them accessible to the entire team. Navisworks can also create issues that can be synced to an issue tracker, but this requires a separate subscription that all users would need to have using ACC >model coordination or via 3rd party plugins which are purchased separately..
Clash automation – for simple or more advanced clash automation where clash tests can have a single or multiple trades involved (ie. Struct Steel vs MEPF) and all clashes will be auto assigned to the correct trade detailer based on system priority through the use of stamp presets. In addition, other data fields such as status, priority, deadline are automatically assigned to each clash & synced to the issue tracker when ready. This saves a tremendous amount of time & monotonous work of sorting through hundreds of clashes and manually assigning them to the responsible party.
Ability to mark up clashes within clash reviewing process
Ability to temporarily transform object location
Ability to switchback from clash to exact location in authoring software
Ability to transform model locations using measure distance tool
Clash groups can specify distance of clashing elements

An example of how clashes in Revizto can be filtered  based on user-defined zones:

An example of a  system priority structure used to create clash test sets to help determine which trade has priority & which trade will need to take action to resolve the conflict

The results of a Revizto clash automation test with clashes filtered by level, auto assigned to correct team member, and synced to the issue tracker

Revizto’s advanced clash automation settings:

Structural steel vs Plumbing clash test performed in Revizto:

Structural steel vs Plumbing clash test performed in Navisworks:

Clash set up

Description	Revizto	Navisworks
Revizto has the ability to easily create search sets straight from the element property. Most model properties are brought into Revizto from the authoring software and it is possible to add multiple values at a time inside the same search string in Revizto and/ or excluding specific searches within the search set. Navisworks does not have the ability to create search sets directly from the property palette – it can only insert (1) property value at a time from a drop down menu of available property values.
Clash type options including various forms of clearance and tolerance clashing for more specific clash workflows3.
Ability to assign clashes to a specific levels, grids, & zones file. This is important so all clashes & issues include the meta data to be easily filterable making it easy to review what is necessary depending on various project execution strategies.
Ability to assign logic to clash tests so clashes get automatically assigned to the correct team members & synced to the issue tracker instantly after it is run.
Ability to detect clashes without models being visible
Ability to group clashes by variety of parameters such as: proximity, system classification, level, zone, etc
Ability to ignore specific search sets

This particular screenshot below showcases the ability of Revizto to add multiple values to the search query at the same time:

Here is  an example of how Revizto can add parameters to search queries directly from the element property palette:

The list of available clash types in Revizto can be seen in the screenshot below:

This is an example of how Navisworks can only add a single value to the search query at a time:

This is an example of how Navisworks can only add a single value to the search query at a time:

Sorting/filtering

Description	Revizto	Navisworks
Clash tests can be filtered in Revizto to show only specific levels that you want very easily. Filter clashes by level, zone, room, status, priority, search set, tag, etc. Navisworks can only filter clashes based on what is inclusive or exclusive of a clash that is selected.
Ability to filter issues by type: clashes vs regular issues. “Non-clash” issues are typically for design, constructability, or field related issues and can be separated from “clashes” that are found through clash detection. Being able to easily filter out “constructability issues” from “clashes” based on type, level, trade, or priority keeps meetings concise and to the point.
Ability to sort clashes based on a variety of different parameters such as level, status, priority, assignee, zone, room, etc
Ability to create custom issue tracking presets or reports via filters such as status, assignee, level, priority, deadline, zone, etc

The example of how Revizto can filter clashes by level can be seen in an image below:

Visualization

Description	Revizto	Navisworks
Easily apply custom appearance profile settings to view clashes based on user preferences. This allows users who may want to see clashes highlighted using certain colors, but also allow for the non clashing elements to show based on a custom appearance profile
Ability to easily apply & share custom appearance profiles to any view on a project
Ability to easily lock the section box or camera view based on user preference making it easy to see where clash is in relation to other objects
Automatically crops section box around the best view of the clash group selected
Ability to see clashes isolated, isolated in transparency, show all
Ability to modify highlighted clash colors
Ability to switch visual styles (render, shaded, wireframe mode)

Reporting/Issue tracking

Description	Revizto	Navisworks
Ability to easily create custom dashboards & reports to keep team members accountable to schedule deadlines. These metrics are easily customizable based on large variety of available parameters such as issue type, assignee, location, status, priority, deadline, etc
Ability to create filter presets within issue tracker to filter issues by a large variety of available parameters
Issue tracking – Revizto issue tracking is instantly updated to all project dashboards & reports when issue status, comments, or markups are made. The built in messenger app allows team members to communicate in real time & attach files or photos. The issue tracking module is available on all devices or via web browser. Navisworks clashes can be saved out as reports in xml, html, or viewpoints but they are static and have no ability to auto assign them to people, set priorities, deadlines, etc. Because there is no ability to communicate with other team members in a common data platform that everyone can access, there is no ability to see track the status of the clash process or reassign it to the correct party making it difficult to hold trades accountable. There are 3rd party plugins or separate Autodesk subscriptions that enable this such as ACC >model coordination, but it is an extremely manual & slow input process, so it is not optimal when it comes to handling large amounts of issues or leveraging data across large teams.

Example of a project dashboard & key benefits:

1. Dashboards enable and drive collaboration
2. Foster transparency and engagement for a common project goal
3. Issued weekly to all project participants including the client
4. Line based charting creates a competitive coordination environment
5. Everything is reported create a sense of accomplishment

User interface

Description	Revizto	Navisworks
Intuitive & low barrier of entry to learn for most users. Simple & elegant design allowing users to switch between simple & advanced tool sets very easily
User preferences are simple & easy to find
Continually creating updates to improve clashing tools and customer experience
View cube – helpful in project orientation relative to True North
Orthographic views
Ability to have app tools on multiple screens
Ability to select objects using a selection window
Ability to dock or auto hide tool palettes to maximize screen space
Ability to display grid lines
Orbit or walk view modes

Interoperability

Description	Revizto	Navisworks
Able to easily import & compress a variety of various file types from commonly used authoring software.
Ability to easily import & compress various point cloud & 3D mesh files.
Integrates with other technology solutions or cloud data sharing sites
Plugins available for most model authoring software to allow direct or scheduled exports to keep models updated
Export file out to .ifc
Export file out to .fbx
Ability to save to NWD which can be viewed in other software applications such as Revit, ACC, Procore via Autodesk Forge model viewer

It should be noted that Revizto does not offer that many options when it comes to exporting in different file types – it can still export out to the IFC or .exe file format, On the other hand, the switchback feature can be used to navigate to the view of the clash in the authoring software, making the navigation process a bit smoother.

Navisworks, on the other hand, uses a slightly different approach – it has the ability to switchback to the location of the clash or you can import the merged model into your model authoring software such as Revit or AutoCAD using its own proprietary NWD file format. This can really be helpful when trying to coordinate your model in relation to the other trades such as centering sprinkler heads on the Architectural RCP along with electrical lighting & mechanical diffusers. Centering & aligning these types of elements is typically done in 2D orthographic views inside the authoring software because they can be centered or aligned more easily than in 3D.

Access/security

Description	Revizto	Navisworks
Easily manage who has access rights to run, create, or manage clash detection. VDC Manager & trade discipline leads are typically the ones who create tests, but access can be given to other team members to create or run their own test as much as they want.
Ability to invite as many project team members as needed to the project & manage roles of each team member. Naviswork Manage requires a designated software license & BIM 360 account license to “pull” other models from the Autodesk BIM 360 cloud platform. Users must have Navisworks Manage to run clash detection, so information is limited to only a handful of VDC specialists to perform it.
Ability to “check out” clash tests to prevent multiple people from running clash detection or modifying the settings of the clash test.
Ability to load & view common 2D & 3D file formats such as dwg, rvt, skp, ifc, etc on the Autodesk construction cloud platform.

It is worth noting here that Navisworks does not offer the ability to control access rights in the first place, it is often delegated to a single individual or handful of people within the company requiring a license for each user.  Since only the users of Navisworks Manage have access to the merged models & clash detection tools,  information is often bottlenecked which defeats the purpose of open cloud collaboration & leveraging data across the team.

Now that we’re done with this last topic from our list, it is time to summarize all of the previous results in order to showcase the strengths and weaknesses of both Navisworks and Revizto.

Navisworks vs Revizto clash detection comparison summary

In Summary, we can safely say that Revizto is a more robust, automated, & collaborative solution than Navisworks in performing clash detection. However, it would also be fair to mention that the decision to use a specific tool for clash detection is not always decided by objective advantages or disadvantages of the software in question.

There can also be plenty of other reasons used for or against a particular decision, and even something as simple as the company being comfortable with their current product or workflow  may keep them  from switching to an  objectively better alternative. This is especially true  for companies that have antiquated workflows & technology standards in place.

Conclusion

Clash detection is an integral part of any construction project strategy, allowing for projects to be much more predictable & effective in both time & cost. The existence of clash detection greatly reduces the chances of expensive rework & surprises downstream, which can be very expensive  at the time of installation.

Clash detection, automation, BIM & data analytics are all part of a significant strategy to modernize and improve the overall value proposition of the AEC industry as a whole. As design assist, design-build, & integrated project delivery methods become more common, being able to take a more holistic & proactive approach to design is critical to the operational efficiency & predictability of any project.

It is difficult to imagine BIM without clash detection since it  is the main reason why coordination can be streamlined and even automated in certain areas now.

There are plenty of different clash detection solutions on the market. Some of them are created to be able to integrate with different modeling authoring software and can only perform clash detection and a handful of other features, some are plugins to software that already have clash detection and offer the ability to track issues, while others are more comprehensive & collaborative with many other tools in addition to clash detection.

The decision on which software to use is really based on what goals the company plans to accomplish in the short or long term, the time & budget constraints they are up against, access to training & material to make informed decisions, and which solution offers the most value to leverage the data they need to those who need access.

We hope that the information presented in this article has helped inform you on the clash detection process & which software solution is best for you.