Capturing a defect in a 3D survey — a crack, a spall, a deformation, a corroded joint — is the start of the job, not the end. The value is in what happens next: assessing the defect, prioritising it against others, planning and executing remediation, and then verifying it was fixed. Doing that traditionally means a 3D model trapped in specialist software that only the surveyor can open, and a separate spreadsheet of defects that drifts out of sync with the model.
A cloud-hosted Nira reality model collapses that into one living document. This guide explains how it works for defect lifecycle monitoring. For the capture that feeds it, see our reality capture service and point cloud survey service.
What Nira is
Nira is a browser-based platform for hosting and collaborating on large 3D reality models — the dense photogrammetric meshes and point clouds produced by a survey. Its significance for defect work is that it removes the software barrier: anyone with the link can open the full-resolution model in a standard web browser, orbit and zoom it, and measure distances, areas and levels directly on it — with no CAD licence, no specialist viewer, and no download.
We host Angell Surveys models on a dedicated Nira workspace; the Highbury Stadium Square facade survey and the Calair Burn catchment survey both have live measurable models behind them.
The defect lifecycle
A defect moves through a predictable lifecycle, and a hosted model supports each stage:
1. Identification. During or after capture, defects are located on the model and tagged — each pinned to its exact 3D position on the structure, not described loosely in a report. A pin carries a description, a photograph, and its location, so there is no ambiguity about which crack on which elevation is meant.
2. Assessment. Because the model is measurable in the browser, a defect can be sized directly — the length of a crack, the area of spalling, the offset of a deformation — by anyone reviewing it, without re-mobilising to site. The structural engineer assesses severity from the same model the surveyor captured.
3. Prioritisation. With every defect tagged on one model, the asset owner sees the whole picture at once — where the defects cluster, which elevations are worst, what to address first. The model becomes the shared basis for the remediation programme.
4. Remediation planning. Contractors quoting or planning the works open the same model, measure their own quantities, and understand access and extent without a site visit — particularly valuable for facades, structures and hard-to-access assets where every site visit is costly.
5. Verification. After remediation, a re-capture is hosted alongside the original. The before-and-after models are compared to confirm the defect was addressed — closing the loop with evidence rather than assertion.
Time-series change detection
The most powerful use is monitoring change over time. A structure or site captured at intervals produces a sequence of models, and differencing successive captures reveals movement that no single snapshot shows:
- Settlement or deformation of a structure between epochs
- Crack propagation — is it growing, and how fast?
- Material loss, erosion or scour progression
- Earthworks or stockpile change — the same principle as our CNI weekly earthworks monitoring, applied to defect geometry
For this to be valid, the captures must be on a consistent datum and capture geometry — which is why monitoring programmes use a fixed control network and consistent platform, and report check-point residuals each epoch (see our QA/QC methodologies guide). Get that right and the differenced models quantify change in millimetres; get it wrong and capture-to-capture noise swamps the real signal.
Why hosted beats a delivered file
The alternative to a hosted model is a delivered file — a point cloud or mesh emailed or shared, that the recipient has to have software and skill to open. In practice that means the model is opened once by the surveyor, screenshots go into a PDF, and the live 3D data dies on a drive. The defect spreadsheet then lives separately and drifts out of date.
A hosted Nira model keeps the 3D data live and shared for the life of the asset programme:
- Every stakeholder — owner, engineer, contractor, planner — works from the same current model
- Defects are tagged on the model, not in a separate document that desyncs
- Measurement is available to everyone, not just the CAD-equipped
- New captures are added to the same workspace, building the time series in place
- Access is by link, controllable and revocable
What we deliver into Nira
For a defect-monitoring engagement, the survey workflow feeds the hosted model:
- Capture by the appropriate method — UAV photogrammetry for facades and large structures, TLS for engineering-tolerance detail, Elios drone for confined voids
- Processing to a dense, textured reality model on a verified datum
- Hosting on the Angell Surveys Nira workspace, link issued to the stakeholders
- Defect tagging as identified, each pinned and described
- Re-capture and comparison at the agreed monitoring interval
- An accuracy basis reported against independent check points, to the RICS Measured Surveys of Land, Buildings and Utilities (3rd edition) bands, so measurements taken on the model are trustworthy
Frequently asked questions
Do stakeholders need special software to use the model? No — that is the point. A Nira model opens in a standard web browser, full resolution, with measurement tools built in. No CAD licence, no specialist viewer, no download. Access is by link.
How accurate are measurements taken in the browser? As accurate as the underlying survey, which is reported against independent check points and a RICS band. The browser measurement reads the same geometry the surveyor captured — it is not a degraded preview.
Can you detect whether a crack is growing? Yes — with consistent-datum, consistent-geometry repeat captures, successive models are differenced to quantify change between epochs. Crack propagation, deformation and material loss are all detectable down to the survey’s accuracy when the monitoring is set up correctly.
What happens to the model after the project? It remains hosted on the workspace for the life of the asset programme, building the time series as new captures are added, and access is controllable and revocable per stakeholder.
For hosted, measurable reality models and defect lifecycle monitoring, see our reality capture service and point cloud survey service. Live examples sit behind our Highbury facade and Calair Burn catchment case studies.