Insights about project management, GIS, and how technology is transforming industries operating in the physical world.
No .prj, so nothing knows what the numbers mean: GDAL prints no CRS, QGIS asks, and the browser viewer assumes WGS 84 and says so. How to tell degrees from UTM metres by looking at the numbers, why an exported longitude of -2171693 is your easting, and the two ogr2ogr lines that fix it.
No .shx and GDAL refuses while the browser opens the file; no .dbf and everything opens with zero attributes and no warning; no .shp and there is nothing to open. What each Shapefile file is, whether it can be rebuilt, and what the viewer and ogrinfo say for each missing one, measured on IBGE data.
Verified list of free geospatial data for Brazil: IBGE meshes and census tracts, INPE's PRODES, DETER and fire hotspots, MapBiomas, ANA hydrography, conservation units, indigenous lands, roads, mining and power plants. Every link tested 15 September 2026, format, measured CRS and licence as printed.
The dBase header gives a Shapefile field name 11 bytes, one a terminator: 10 characters. GDAL warns and cuts, colliding names become nome_da_un, nome_da__1 and nome_da__2, and the viewer shows the short one. On GDAL 3.13.3 a complete .shp.xml restores the name; a partial one is ignored silently.
A WMS that works in QGIS and fails in your web map is almost never broken. Mixed content, CORS, a user-agent rule, a GetCapabilities that answers with HTML, a WMTS URL in the WMS box: the short list of real causes, each with the symptom you see and the fix that works.
SIRGAS 2000, SAD69, Corrego Alegre, MAGNA-SIRGAS, POSGAR 2007 — every code here was read out of GDAL 3.13.3 on 11 September 2026, not from memory. Which UTM zone covers which Brazilian state, why a distance measured in EPSG:3857 runs 9% long at São Paulo, and how to convert.
A phone writes the GPS fix into a photo's EXIF; WhatsApp and Instagram strip it, AirDrop and a cable copy keep it. How to read GPSLatitude and its hemisphere, why a screenshot has no location, how to map a folder of photos for free in the browser, and how to remove the tag before you share.
The .dbf has no encoding of its own; a five-byte .cpg names one. Without it every reader guesses, and GDAL and the browser guess differently: Latin-1 read as UTF-8 gives Amap�, UTF-8 read as Latin-1 gives Amapá. Both reproduced, with the one-line .cpg fix, the ogr2ogr recode and the trap.
Collect and edit in GeoPackage, publish to the web in GeoJSON, send a Shapefile only when the other side insists. The evidence: the IBGE 27-state mesh converted three ways and measured on eight criteria, from bytes loose and zipped to the .cpg encoding trap, the EPSG code and viewer load time.
You do not need QGIS to open a GeoJSON file. Drop it on a free browser viewer and it draws with its attribute table; nothing uploads. The steps quoted from the live tool, the four things that go wrong (including the silent wrong-place crs case), test files, and when you actually need QGIS.
A Shapefile is five files, one shape type and a .dbf from 1998. We built them with GDAL 3.13.3, deleted the sidecars one by one, read the .dbf bytes and quoted every error: names cut at 10 characters, Latin-1 by default, NULL equals empty, the .prj that puts your layer in the ocean, and the fixes.
What GeoJSON is, what RFC 7946 changed, why a file exported in UTM lands in the North Atlantic with no error, the ogr2ogr flags that matter, and the real size of the format measured on the 27 states of Brazil. Every number comes from a dated lab run, not from a spec.