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Maps · head to head

Correlator3D vs GRASS GIS

Correlator3D logo

Correlator3D

Maps

SimActive photogrammetry with a published price list and a perpetual licence still on sale

From
$295/month
Rated
-
Full reviewWebsite
GRASS GIS logo

GRASS GIS

Maps

Long-running open source geospatial analysis engine for raster, vector and terrain processing

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only GRASS GIS has a free tier, so it costs nothing to try first.
  • Each has a real cost: Correlator3D the standard licence caps at 61 megapixel sensors, so an operator moving to a medium or large format camera has to buy a different and separately quoted licence rather than paying an upgrade fee.; GRASS GIS the location and mapset data model requires importing data into a structured database with a fixed coordinate system before analysis, which is a real barrier for anyone used to opening files directly.
  • They diverge on capability: Correlator3D covers Aerial triangulation, GRASS GIS covers Raster analysis.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Correlator3D and GRASS GIS actually diverge.

Attributes where Correlator3D and GRASS GIS differ
AttributeCorrelator3DGRASS GIS
Starting price$295/monthFree
Pricing modelOne-time purchaseOpen source, no licence fee
Free tierNoYes
PlatformsWindowsLinux, Windows, macOS

Identical on both: user rating (Not yet rated), category (Maps).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Correlator3D

  • Aerial triangulation
  • DSM and DTM generation
  • Orthomosaic production
  • Point cloud and 3D mesh output
  • Feature extraction
  • GPU acceleration
  • Satellite imagery support
  • Batch and unattended processing

Only in GRASS GIS

  • Raster analysis
  • Hydrological modelling
  • Terrain analysis
  • Vector topology
  • Temporal framework
  • Image processing
  • Python API
  • QGIS integration

What people use each for

The jobs each tool is most often brought in to do.

Correlator3D

  • An aerial survey company processing large photographic blocks where per-project cloud credits would be more expensive than owning a licencenot GRASS GIS
  • A national or regional mapping agency that needs software it can run offline on classified or restricted imagerynot GRASS GIS
  • A drone service provider producing bare-earth terrain models for volumetrics and corridor mapping at high throughputnot GRASS GIS
  • An organisation that wants a perpetual licence because a multi-year subscription cannot be justified against its capital budgeting rulesnot GRASS GIS

GRASS GIS

  • A hydrologist delineating watersheds and modelling flow accumulation over a large digital elevation modelnot Correlator3D
  • A research group building a reproducible time series analysis of satellite imagery that must be rerunnable years laternot Correlator3D
  • An environmental agency running viewshed and solar radiation analysis for planning assessments without buying commercial GIS seatsnot Correlator3D
  • A QGIS user who needs a specific processing algorithm that only exists in the GRASS toolboxnot Correlator3D

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Correlator3D

  • The standard licence caps at 61 megapixel sensors, so an operator moving to a medium or large format camera has to buy a different and separately quoted licence rather than paying an upgrade fee.
  • It is Windows desktop only with no cloud processing option, so throughput is bounded by the workstation and GPU you buy, and there is no way to burst capacity for one large job.
  • There is no collaboration layer, client portal or field application, so deliverable sharing, review and version control all have to be handled by other software.
  • The interface and workflow are built for photogrammetry specialists; an occasional drone operator will find the learning curve steeper than a consumer-oriented mapping package.
  • The perpetual licence includes only one year of support and updates, and staying current afterwards means paying maintenance, so the headline $5,900 is not the whole long-term cost.

GRASS GIS

  • The location and mapset data model requires importing data into a structured database with a fixed coordinate system before analysis, which is a real barrier for anyone used to opening files directly.
  • The native graphical interface is dated and inconsistent compared with QGIS or ArcGIS, so most users end up running GRASS through QGIS and never learn the tool they are actually depending on.
  • There is no vendor, so contractual support, service levels and liability do not exist by default and must be arranged with an independent consultancy that may not cover your jurisdiction.
  • Cartographic output and map layout are weak relative to the analysis capability, meaning a second tool is always needed to produce a publishable map.
  • Module naming and argument conventions are idiosyncratic and long-standing, so scripts are durable but the learning curve is steep and transferable skills from other GIS packages help less than expected.

Pricing, plan by plan

Correlator3D

$295/month
  • Monthly subscription$295/month
    • Unlimited images
    • Sensors up to 61 megapixels
    • All modules and tools
  • Yearly subscription$2950/year
    • Unlimited images
    • Sensors up to 61 megapixels
    • All modules and tools
  • Permanent licence$5900/one-time
    • Perpetual licence
    • Unlimited images up to 61 megapixels
    • All modules and tools
  • Permanent floating licence$6400/one-time
    • Perpetual floating licence shared across machines
    • Unlimited images up to 61 megapixels
    • One year of support and updates included

GRASS GIS

Free
  • GRASS GISFree
    • GNU GPL licence
    • All modules included
    • No user or seat limits

Which should you pick?

Choose Correlator3D if

  • You need aerial triangulation.
  • You work on Windows.
  • You also want dsm and dtm generation.
Correlator3D review

Choose GRASS GIS if

  • You need raster analysis.
  • You want to start without paying.
  • You work on Linux, Windows, macOS.
  • You also want hydrological modelling.
GRASS GIS review

Questions people ask

Is Correlator3D or GRASS GIS better?
Neither clearly leads. Correlator3D starts at $295/month and GRASS GIS at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Correlator3D or GRASS GIS?
GRASS GIS has a free tier; the other does not. Paid plans start at $295/month for Correlator3D and Free for GRASS GIS.
Does Correlator3D or GRASS GIS run on more platforms?
Correlator3D runs on Windows. GRASS GIS runs on Linux, Windows, macOS.
Can I use GRASS GIS for free?
Yes. GRASS GIS has a free tier, so you can try it without paying. Correlator3D starts at $295/month.
What is Correlator3D best used for?
Correlator3D is most often used for an aerial survey company processing large photographic blocks where per-project cloud credits would be more expensive than owning a licence, a national or regional mapping agency that needs software it can run offline on classified or restricted imagery, a drone service provider producing bare-earth terrain models for volumetrics and corridor mapping at high throughput, an organisation that wants a perpetual licence because a multi-year subscription cannot be justified against its capital budgeting rules. Of those, an aerial survey company processing large photographic blocks where per-project cloud credits would be more expensive than owning a licence and a national or regional mapping agency that needs software it can run offline on classified or restricted imagery are not what GRASS GIS is typically brought in for.
What can Correlator3D do that GRASS GIS cannot?
Correlator3D covers Aerial triangulation, DSM and DTM generation, Orthomosaic production, Point cloud and 3D mesh output. GRASS GIS covers Raster analysis, Hydrological modelling, Terrain analysis, Vector topology.

Answered from the vendors’ own pages

Correlator3D: Can I still buy a perpetual licence?

Yes. $5,900 for a permanent licence and $6,400 for a permanent floating licence, each including a year of support and updates.

GRASS GIS: Who maintains GRASS GIS?

An international volunteer and academic developer community under the Open Source Geospatial Foundation. It originated at the US Army Construction Engineering Research Laboratory in 1982.

Correlator3D: What limits the standard licence?

Sensor resolution, up to 61 megapixels. Medium format, large format and satellite imagery need separately priced licences.

GRASS GIS: Can I buy commercial support?

Not from a vendor. Independent consultancies in the OSGeo ecosystem offer paid support and development, and availability varies by region.

Correlator3D: Is there a cloud version?

No. Processing runs on your own Windows workstation. SimActive offers a data processing service as an alternative to buying the software.

GRASS GIS: Do I need to use its interface?

No. Most people run GRASS algorithms through the QGIS processing toolbox or from Python.

Correlator3D: Does it handle satellite imagery?

Yes, under a separate satellite licence class quoted on request.

GRASS GIS: Is it suitable for production use?

Yes for analysis pipelines, and it is used by agencies and research institutions. Plan for community support rather than a service level agreement.

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