GIS maps are not pictures. They are stacks of layers, each holding measured geometry plus attributes you can query — filtered and analysed rather than simply looked at. That is the difference between a GIS map and a JPEG of the same site.
The part that gets less attention is the part that decides whether the system is any good: every layer in a GIS is drawn on top of a base layer, and that base layer came from somewhere, on some date. In a lot of organisations it came from an aerial capture several years old, and nobody has checked. Refreshing it is the core of our GIS and spatial analytics work.
What makes a GIS map different from an image
Three things, and they compound.
Layers. A drainage layer, a property layer, a vegetation layer, a road centreline layer, an aerial image underneath the lot. Each is independent — switch it on or off, reorder it, style it differently. A PDF plan has all of that flattened into one picture, permanently.
Attributes. Every feature carries a record. A pit is not just a dot; it is a dot with an asset ID, a material, an installation date and a condition rating. A GIS is a database that happens to draw itself.
Queries and analysis. Because the geometry is measured and the attributes are structured, you can ask questions: which assets sit within 50 metres of this watercourse, which parcels are affected by this overlay, how much tree canopy this precinct lost since the last capture. A static image cannot answer any of those.
Underneath it all sits a coordinate system, which lets a layer captured by one organisation sit correctly on top of a layer captured by another. Get that wrong and everything else is decoration.
Why GIS maps go stale: the base data underneath them is old
Here is the uncomfortable question to put to your own GIS: what is the capture date of the imagery and terrain everything else is drawn on?
For a lot of councils, utilities and consultancies the honest answer is several years ago — a statewide programme, a project flown for a different purpose, or a free web basemap with no stated currency at all. Meanwhile the site has changed. Subdivisions have gone in. A depot has been resurfaced. Vegetation has grown, or burned, or been cleared.
Nothing in the software tells you this. The map still renders. The layers still line up with each other, because they are all wrong in the same direction. The failure is quiet, and it shows up as decisions made against a site that no longer exists — an inspection routed to a demolished building, a stormwater model run over terrain since cut and filled, a vegetation assessment argued from imagery predating the works in dispute. Every downstream analysis inherits the age of its base layer.
The practical response is unglamorous: capture the site again. A current aerial capture over a defined area of interest is the cheapest way to refresh the layer everything else sits on, and it is cheap precisely because it is narrow. You are not re-flying the state. You are re-flying the hectares that changed, at the resolution your work needs, on a date you can name.
A refreshed base layer with a documented capture date, retained metadata and a stated coordinate system is also a defensible record of site conditions on that date.
What the data actually is, and what formats it comes in
Aerial capture produces several distinct datasets, and format is usually where interoperability succeeds or fails.
Orthomosaic (GeoTIFF). Hundreds of overlapping photographs, geometrically corrected and stitched into a single image where every pixel sits in its correct real-world position — so you can measure across it. As a GeoTIFF it carries its own georeferencing and drops straight into QGIS, ArcGIS or a corporate spatial database. This is the workhorse base layer.
Elevation surfaces (GeoTIFF raster). A digital elevation model as a gridded surface — for slope, aspect, catchment delineation, overland flow and volume calculations. Specify whether you need the surface as captured, including canopy and structures, or bare earth with those stripped out. Hydrology needs bare earth.
Contours and 3D strings (DXF/DWG). For the engineering side of the house, who work in CAD rather than GIS. Contours, spot levels and breaklines in your project datum, ready for Civil 3D or 12d.
Point clouds (LAS/LAZ). The full measured three-dimensional dataset, before simplification. Large files, but your team can re-derive surfaces and take sections later without re-flying. LAZ is the compressed form.
Vector features (shapefile / GeoJSON). Digitised features — building footprints, kerb lines, canopy polygons, hardstand areas — with attributes attached. Shapefile remains the lingua franca of corporate GIS despite its age; GeoJSON suits web mapping.
Tell us at briefing which software the data has to open in and who else will consume it. Reformatting after delivery is avoidable work, and lossy conversions are where attributes quietly disappear.
GDA2020, MGA zones, and why the datum decides everything
Australian spatial data has moved from GDA94 to GDA2020, and the difference is not trivial — roughly 1.8 metres, because the datum was updated to account for continental drift since GDA94 was defined. Horizontal position is typically expressed in MGA2020 zone coordinates: most of Victoria falls in Zone 55, western Victoria in Zone 54. Heights are usually referenced to the Australian Height Datum (AHD), which is separate from the horizontal datum and has to be specified separately.
What this means in practice: if we deliver in GDA2020 and your corporate GIS still holds legacy layers in GDA94, the new capture will sit nearly two metres off your existing asset layer. Everything looks subtly wrong — pits beside the road instead of in it, footprints overhanging boundaries — and someone spends a day assuming the new data is at fault.
It usually isn’t. It is a datum mismatch, avoidable by asking one question before the flight rather than after delivery: which datum, which zone, which height datum, and does that match every other layer this sits alongside? If your organisation is mid-transition and holds a mix, say so — we can deliver in both, which costs far less at processing than reprojecting later.
Who this is for
Councils and local government asset teams — asset registers, tree canopy, road and drainage networks, open-space management, before-and-after records for capital works.
Utilities — corridor and easement condition, vegetation clearance around infrastructure, access planning, site state before and after works.
Environmental consultants — vegetation extent and change over time, erosion and watercourse condition, rehabilitation monitoring. Repeat capture on the same flight plan is where this gets powerful: change becomes measurable rather than arguable.
Planners — current site conditions for assessments and reports, rather than whatever the free basemap holds.
Engineering firms — existing-conditions surfaces for design, earthworks volumes, progress records across a construction programme.
The common thread: they all already have a GIS. What they are short of is current, correctly referenced spatial data to put in it.
What we do, and what we don’t
We capture, process and deliver the data in the formats your GIS expects — orthomosaics, elevation surfaces, point clouds, contours and vector features, in your datum and zone, with metadata intact. We fly under CASA-licensed operations from our base in Hampton Park, south-east Melbourne, and travel interstate by arrangement.
We are not a GIS consultancy. We do not build, configure or administer your GIS platform, and we do not manage your asset database. That is consultancy work; we supply data to firms doing it.
We are also not licensed land surveyors. Anything requiring legal boundary definition — title boundaries, easements, subdivision, any dimension certified for a statutory purpose — stays with a licensed surveyor. Our data provides current spatial context; it does not define a boundary.
Frequently asked questions
What are GIS maps used for?
GIS maps let organisations store, query and analyse spatial information rather than just view it. Councils use them for asset registers and open-space management, utilities for network and easement condition, environmental consultants for vegetation and change monitoring, and planners for site assessment. Because every feature carries attributes, a GIS answers questions — what is within this distance, what changed since when — that a static map cannot.
What is the difference between GIS data and an aerial photograph?
An aerial photograph is an image. GIS data is measured geometry with attributes attached and a defined coordinate system, so it can be queried, analysed and combined with other layers. An orthomosaic sits between the two: it looks like a photograph but is geometrically corrected and georeferenced, so you can measure across it and it lands in the correct real-world position.
How often should GIS base imagery be updated?
It depends on how fast the area changes and what decisions rely on it. Sites under construction or active management may warrant capture every few months; stable rural areas may be fine for years. The useful test is not elapsed time but whether the imagery predates changes that matter — works completed, vegetation cleared, assets installed. If it does, the base layer is misleading every analysis drawn on top of it.
What file formats do you deliver spatial data in?
GeoTIFF for orthomosaics and elevation rasters, LAS or LAZ for point clouds, DXF or DWG for contours and 3D strings, and shapefile or GeoJSON for digitised vector features. All delivered in the coordinate system and datum you nominate, with metadata retained. Tell us which software the data has to open in before capture, not after.
Why does GDA2020 matter for my GIS?
Because GDA2020 and the older GDA94 differ by roughly 1.8 metres. If new capture is delivered in one datum and your existing layers sit in the other, everything will be offset by that amount and nothing will align correctly. Specify your datum, MGA zone and height datum at briefing so the delivered data drops straight onto your existing layers.
Do you build or manage GIS systems?
No. We capture, process and deliver spatial data in the formats your GIS expects. We do not build, configure or administer GIS platforms, and we do not manage asset databases — that is GIS consultancy work, and we regularly supply data to firms doing exactly that. Anything requiring legal boundary definition remains work for a licensed surveyor.