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LidarKit

Inspect LAS and LAZ files without opening the points

Header, coordinate system, every record, and what the point format carries. From a file on your disk or a URL — with nothing uploaded and no points downloaded.

Drop a LAS or LAZ file to inspect

or choose a file

Reads the header and records only · a 20 GB file takes the same few kilobytes as a 2 MB one

Or inspect a hosted file without downloading it — the header comes down in a few range requests:

What you can find out

Most questions about a delivered LiDAR file are answered by its header, not its points. This tool shows the header the way the specification lays it out, and then decodes the parts that are usually left as opaque numbers:

  • Which coordinate system is this? The EPSG code, projection, datum, units and vertical system, decoded from the file's WKT record or its GeoTIFF keys — and a plain statement when the file has none.
  • What is actually in each point? GPS time, RGB, near-infrared and waveform availability, the classification range and the maximum return number, all fixed by the point data record format.
  • What are the extra bytes? Extra-bytes descriptors are decoded to field names, data types and descriptions — or flagged as undocumented when the record is missing.
  • Is it LAZ, and how was it compressed? The LASzip record gives the compressor variant, version, chunk size and item layout.
  • Is it COPC? The copc info record is decoded and the rest of the layout is checked against the COPC specification.
  • Does the header agree with itself? Point counts against the by-return table, the point format against the version, the WKT flag against the records actually present, the VLR count against what can be read.

Read, derived, decoded

Every value carries one of three labels. Read values are copied from the file as stored. Derived values are arithmetic on read values: an extent, a byte total, a density. Decoded values are stored codes interpreted through the LAS specification or a lookup table — a format number turned into "has RGB", an EPSG number turned into a name. The distinction matters most for the coordinate system: a CRS that software inferred and a CRS the file declares look identical on screen and are not the same thing at all.

Nothing on this page is guessed from the coordinates themselves. If the file stores no coordinate system, the inspector says so, and stops there.

Inspecting hosted files

Paste the URL of a LAS or LAZ file and the inspector reads its header with HTTP range requests — typically under ten kilobytes of traffic for a file of any size. The host has to allow cross-origin requests and byte ranges; most object stores and tile servers do, and the tool names the specific problem when one does not. Your browser talks to that host directly. Nothing passes through this site.

This is the practical way to check a file on S3 before pulling two gigabytes down, or to confirm what a data portal is really serving under a link.

What it deliberately does not do

  • It does not read point records, so it cannot report which classes are actually present or the real intensity range. The viewer's statistics panel reads every point and counts each class if you need to see that.
  • It does not reproject, assign or "fix" a coordinate system.
  • It does not edit the file. To change formats, use the converter.

Frequently asked questions

What does the LAS inspector read?
The public header block and every variable length record (VLR and EVLR) — version, point format, point count, scale, offset, bounds, coordinate system, generating software, and the decoded contents of known records such as WKT, GeoTIFF keys, LAZ parameters, COPC info, extra bytes and classification lookups. It never reads the point records themselves.
How can it inspect a 20 GB file instantly?
Because everything it shows lives in the first few kilobytes of the file plus, for LAS 1.4, a short directory at the end. The header is a fixed 227 to 375 bytes and the records follow it directly, so a 20 GB file costs the same handful of reads as a 2 MB one. Point data is never touched.
Can I inspect a file from a URL without downloading it?
Yes, if the host allows cross-origin requests and byte ranges. The inspector asks for the header and record regions with HTTP range requests, so a 2 GB file on S3 or a tile server is read with a few kilobytes of traffic. If the host blocks cross-origin reads the inspector says so rather than failing silently, and you can download the file and drop it in instead.
What do 'read', 'derived' and 'decoded' mean next to each value?
Read means the value is copied from the file exactly as stored. Derived means it is arithmetic on read values — an extent from min and max, a density from count and area. Decoded means a stored code was interpreted through the LAS specification or a lookup table, such as a point format number turned into 'has RGB' or an EPSG code turned into a name. The labels exist so an inferred coordinate system is never mistaken for a stored one.
How does it find the coordinate system?
From the file's own records. LAS 1.4 stores an OGC WKT string in record 2112 of LASF_Projection; older files store GeoTIFF keys in records 34735 to 34737. The inspector decodes both, prefers WKT when present as the specification requires, and reports when a file carries both and they disagree. If neither record exists it says no coordinate system is stored — it does not guess one from the coordinate values.
Is a warning in the Checks section an error?
No. Checks report where the header is inconsistent with itself or with the specification — a point format the declared version does not define, a WKT flag with no WKT behind it, return counts that do not add up to the point count. Many such files open fine in most software. The checks tell you where to look; they do not declare a file broken.
Does it tell me whether a file is COPC?
Yes. A COPC file is LAZ 1.4 with point format 6, 7 or 8 and a copc info record as its first VLR. The inspector decodes that record — octree centre, root spacing, hierarchy location — and confirms whether the rest of the file meets the COPC layout, or warns when a copc record is present but the file cannot actually be streamed.
Are my files uploaded?
No. There is no server. The file is read with the browser's File API on your own machine, and for a URL your browser fetches the bytes directly from the host you name — they never pass through this site. The 'Copy as JSON' button gives you the full report to paste into a ticket or a script.
What is a VLR?
A variable length record: a block of metadata between the header and the point data, identified by a user ID and a record ID. The coordinate system, LAZ compression parameters, extra-bytes descriptions and classification lookups all live in VLRs. LAS 1.4 adds extended VLRs (EVLRs) after the point data for records larger than 64 KB, such as the COPC hierarchy.
Which LAS versions and point formats are supported?
LAS 1.0 through 1.4 and point data record formats 0 through 10, including the waveform formats 4, 5, 9 and 10 that the converter and viewer here do not open. Inspection needs only the header, so formats the other tools refuse are still fully described.

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