Why a Mosaic May Look Incomplete

Use this when

Your mosaic generated successfully but the result has dark gaps, smeared or streaky areas, or sections that look distorted.

Common reasons

Not enough GPS coverage

Each ping is placed using the boat's GPS coordinates. If the GPS signal dropped out for a stretch, the pings from that section have no reliable position and are skipped. The mosaic will have a gap where that data is missing.

The boat was moving too slowly

Below about 0.9 knots, GPS course-over-ground becomes too noisy to reliably derive the boat's heading. HumVision still attempts a best-effort mosaic, but the result can smear or streak where the low-speed section falls. A quality warning appears at the top of the Mosaic view when this happens.

Sharp turns or heading jumps

When the heading changes by more than 12 degrees between consecutive pings, those pings are skipped. This prevents tight turns from producing long diagonal streaks across the mosaic. The affected area shows as a gap or a visible seam in the scan.

GPS jitter

Small but rapid GPS position jumps cause the heading calculation to oscillate. This can produce a mosaic with a wobbly or starburst pattern along the boat track, even at normal speed. Enabling GPS smoothing (on by default) reduces this, but recordings with poor GPS antenna placement may still show the effect.

The survey area is very large

HumVision caps the mosaic at 50 million pixels. For large surveys at high resolution, the resolution is automatically reduced until the grid fits within that limit. At a lower resolution, fine detail is lost and the image may look coarser than expected.

How to check

1. Open the recording and go to the Mosaic view.
2. Look at the quality notice below the progress bar after generation. It names the specific reason pings were skipped — low speed, invalid GPS, or heading jumps.
3. Switch to the Map view and inspect the GPS track. Long straight sections with minimal jitter produce the best mosaics. Sections where the track doubles back on itself or has large position jumps correspond to gap areas.

What to do next

• GPS gaps — nothing can be done after recording. If the gap is in a critical area, consider re-scanning that section.
• Low speed — HumVision still produces a best-effort result. If the smearing is unacceptable, the recording will need to be re-captured at a higher speed.
• Heading jumps — these are usually tight turns at the ends of passes. They are expected and the gap is cosmetically normal.
• GPS jitter — GPS smoothing is on by default and addresses most jitter. Recordings from units with a known GPS antenna issue will not improve without new hardware.
• Reduced resolution — switch to Draft quality if you only need a quick overview of the whole survey area, or split very large recordings into shorter segments before generating at Standard or High.