Are your latitude and longitude the right way round?
Both readings, side by side
Plotting your points on a map is a commodity — QGIS and geojson.io will both do it for free.
What neither will do is plot the other reading: the same two columns exchanged. That is
the one comparison that settles the question, because a swap is only invisible until you see
where it puts you.
Nothing here is uploaded. The coastline and the reference
density are static files this page fetches once; your numbers are parsed, plotted and discarded
in your own browser. There are no basemap tiles — a tile request would send
your survey's bounding box to a third party, which would make that promise a sentence rather
than a property.
As mappedcolumn 1 → latitude
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Columns exchangedcolumn 1 → longitude
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Loading the reference layer…
Your two columns
One point per line, two numbers separated by a comma,
tab or space. Paste straight out of a spreadsheet.
How the reading is decided
Two of the three checks below need no reference data at all — they are arithmetic on your own
numbers, and when one of them fires the answer is proved rather than suggested.
Out of range. A latitude outside ±90 cannot be a latitude. If one reading
is impossible and the other is not, there is nothing left to weigh.
Everything on one line. Points that fall on a perfect diagonal, or collapse
to a single row or column, usually mean a column was repeated or an index was read as a
position.
Density, not presence. Where both readings are possible, we compare each
against how many records already exist nearby. Presence decides nothing —
almost every cell on Earth holds at least one record, so "is there anything here" answers yes
in the middle of the Atlantic. The comparison is how many.
A disagreement is not a verdict. If your site really is in
a thinly-recorded place, the sparse reading may be the correct one — that is exactly what a
survey of an under-sampled area looks like, and it is often the point of the survey. This page
shows you the comparison and names which check fired. It does not overrule you, and it does not
change your file.
What the reference layer costs
Measured, not estimated — these come from the asset this page just fetched.
Item
Detail
Size
Plot time at real row counts
Runs in your browser, on your hardware, right now. A survey is rarely more than a
few thousand points; the larger rows are there to show where canvas actually starts to hurt.