3.5 Data Centers

Why Data Centers Are Different

The geometry is dominated by rack rows, each visually identical to the next. Floor markings and structural columns are the only natural features that distinguish one position from another along an aisle, so SLAM cannot rely on rack geometry to know where it is.

These sites are also scanned repeatedly, often quarterly, to track equipment changes and as-built drift. Every visit must align with the last and with every future one. That places long-term consistency requirements on target placement, route, and reference geometry that one-off scans do not have, so the technique here is more rigid. Departures compound across visits and degrade the whole engagement.

Route Strategy Through Aisles

Speed and Posture

• 1.6 ft/s in all aisles. Rack faces on both sides create a low-feature environment throughout. Slower is fine; faster is not.
• Hold posture consistent along the row. Rotating mid-aisle to face one rack changes the view of both rows at once and introduces alignment artifacts.
• Hold the scanner at least 15 cm (6 in) clear of your body. Body occlusion in narrow aisles is significant; both rack rows must stay in view.

Aisle Coverage

• Walk every aisle. Do not skip cold aisles if hot aisles are done. Skipping produces weaker 3DGS and incomplete point cloud on the unwalked side of every skipped row.
• Vary scanner height between aisles. One aisle at chest height, the next at overhead height, changing gradually over several feet. This gives each rack row at least two viewing heights.
• Loop back through the cross-aisle at the end of every row to reset accumulated drift before the next corridor.

Target Placement

• Space targets every 30 to 50 m (100 to 165 ft), about one per 3 to 5 aisles.
• L2 Pro magnetic steel targets attach to rack panels in seconds, hold reliably, and leave no residue. They are the preferred type here.
• K2 adhesive reflective sticker targets work too but need adhesive. Some operators prohibit adhesive on rack surfaces; verify first and plan removal so no residue remains.
• Neither is a survey GCP by default. Both are high-contrast SLAM anchors. For absolute coordinates, supply surveyed positions in LixelStudio.
• Place each target where the scanner can approach within 1 to 2 m (3 to 6 ft) and circle it. Targets behind equipment lose most of their value.
• Keep targets off hot-aisle vents and airflow paths. Turbulent air vibrates an adhesive sticker and can shift it mid-scan; magnetic attachment to a steel panel is the most stable mount.
• Mark every target in LixelGO during the scan. Unmarked targets are visible in the cloud but unused for SLAM correction or georeferencing.

RTK and Georeferencing Indoors

Most white space has no GPS signal, so georeferencing depends on carried-in RTK and ground control points.

Indoor RTK Reality

• Initialize RTK outdoors and carry it in. Reach Fixed at the entrance with clear sky, then carry the scanner into the white space.
• RTK drops at the first overhead structure. Indoors the scanner falls out of Fixed almost immediately; the indoor georeferencing relies on the last Fixed position.
• Unfixed-gap tolerance differs by device. The L2 Pro holds about 100 m (330 ft) of unfixed travel before georeferencing degrades; the K2 holds about 50 m (165 ft). Beyond these, expect coordinate drift.
• Past the device's tolerance, GCPs are required. RTK alone is insufficient for whole-facility georeferencing beyond compact server-room scale.

Ground Control Point Strategy

• GCPs need surveyed coordinates, not just placement. Without them, a control point is an anchor target with a known location, useful for SLAM but not for absolute georeferencing.
• Place GCPs every 50 m (165 ft) for K2 and every 100 m (330 ft) for L2 Pro. Closer improves accuracy and adds redundancy if one fails to mark cleanly.
• Use the same coordinate system as the carried-in RTK base. Mixing systems forces transformation in processing and loses precision.
• Document GCP positions and coordinate system in the deliverables. Future rescans must reuse the same control points.

Permission and Access

• Confirm GCP placement permission before the scan. Many operators prohibit markers on raised-floor tiles, rack surfaces, or structure. Identify acceptable zones in a pre-scan walkthrough.
• Adhesive removal is mandatory in many agreements. Remove sticker targets and tape at session end.
• Photography and floor-plan access often require escort and time limits. Plan documentation inside the access window.

Three-Pass Coverage for High-Value Spaces

For detailed deliverables (capacity planning, equipment audits, change tracking), three passes substantially improve point cloud density and 3DGS quality.

• Pass 1, chest height, about 1.5 m (5 ft): primary SLAM loop, every aisle. The foundation pass.
• Pass 2, overhead, about 2.1 to 2.4 m (7 to 8 ft): rack tops, overhead cable trays, lighting, ceiling. Same aisles, same direction.
• Pass 3, low, about 0.6 to 0.9 m (2 to 3 ft): raised-floor detail, under-rack equipment, floor-level cable runs.

All three are one continuous session. Keep height consistent within each pass and change gradually between passes.

Recurring Rescans

The original scan sets the baseline; each rescan captures change. For change detection to work, every scan must align with the baseline to sub-inch precision. Match the baseline on three things.

Targets

• Same positions as the baseline. Record them with floor coordinates, rack identifiers, or annotated photographs so any operator can reproduce them.
• If a position is gone (rack moved or replaced), place a substitute at the closest equivalent, document the change, and note it for future visits.
• Photograph each placement with rack and target ID before the scan. Photos guide future placement better than written coordinates.

Route and Boundaries

• Walk the same aisles in the same order, at the same speed and posture. A different pace introduces density differences that complicate change detection.
• Start and end at the same locations as the baseline, within a few feet.
• Match the baseline's session boundaries if the site needs multiple sessions: same count, same locations, same overlap zones. Each new session must share at least 15 m (50 ft) of geometry with the session it merges with.

Before You Leave Site

Access windows are restricted and return visits are expensive. This checklist catches the common failures before the window closes.

• Scan stopped cleanly: LED solid green before power-off, no mid-session error.
• Duration matches plan: within 15 percent of the estimate for the area covered. A large gap is worth investigating before leaving.
• Preview shows no aisle kinks or pod-boundary discontinuities. Check at the cross-aisles between every pod section.
• Every aisle is present in the preview, shown as parallel rack rows.
• Targets marked: every placed target marked in LixelGO during the scan.
• Targets and tape removed per operator agreement. Photograph the removed state.
• GCP positions documented with the survey method used.
• Photo log captured: each placement with rack and target ID, plus notable equipment changes since the baseline.