Subsampling Rate (Approx.)¶
What does "Subsampling rate (approx.) ≥" mean?¶
When you see the label Subsampling rate (approx.) ≥ X% (e.g., ≥ 5%) in the viewer, it indicates that CartoScope is currently employing data thinning to maintain performance.
Breakdown of the Term¶
- Subsampling rate: This is the ratio of valid data currently loaded and rendered in your view compared to the total full-resolution data available for that area.
- "Approx." (Approximate): The system calculates this ratio based on data size (bytes) rather than a raw count of individual molecules or cells. While highly correlated, file size is an effective proxy but not an exact count, hence "approximate".
- "≥" (Greater than or equal to): This symbol is crucial. It means the displayed fidelity is at least the percentage shown, but effectively could be higher.
- Why? CartoScope loads data in discrete zoom levels (powers of 2). If your current view is between two zoom levels (e.g., zoom 4.5), the system loads the tiles for the deeper level (zoom 5) to ensure you have sufficient detail. Therefore, you are viewing "at least" the resolution calculated for that level, and often a bit more than the strict mathematical minimum for your exact viewport.
Why is this happening?¶
Spatial omics datasets can contain hundreds of millions of points. Attempting to render 100% of these points when zoomed out to the whole tissue would: 1. Overwhelm your browser's memory, possibly causing a crash. 2. Make the map interaction laggy and unresponsive. 3. Provide no visual benefit, as millions of points would simply overlap into a solid block of color at that scale.
Is the visualization accurate?¶
Yes. The subsampling algorithms are designed to preserve the spatial distribution and relative density of the data. You can trust the macroscopic patterns (clusters, tissue structures, expression gradients) you see even at low sampling rates.
How do I see 100% of the data?¶
To see the full, raw data: 1. Zoom In: detailed data is loaded dynamically. 2. Watch the rate indicator increase (e.g., ≥ 25%, ≥ 50%). 3. Eventually, the label will disappear or reach 100%, indicating you are viewing the raw data at full resolution.