Author Archives: Gordon S

Esri Releases Historical Imagery – Wayback

Have you ever looked at the Esri Imagery basemap and wished you could see the changes over time. Esri for a long time has only provided the most recent imagery they have access to for your area of interest.

Well now in the ArcGIS Living Atlas Esri is providing all their historical imagery for your area of interest. Entitled the WayBack Imagery collection Esri providing both an exciting web application World Imagery Wayback which allows you to see the changes in the imagery over time and allows you to select an image and add it to your ArcGIS Online site as well as a Living Atlas group Wayback Imagery group which will allow you to see all the different epochs of  imagery.

Go have a look I’m sure you’ll find it useful.

Gordon

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GDA94, GDA2020 and WGS84; The projection dilemma

Progress supporting GDA2020:

The Intergovernmental Committee on Surveying and Mapping (ICSM) & Geoscience Australia (GA) recently released the definitions for the GDA2020 datum and associated projected coordinate systems covering Australia and its territories. Esri Australia has been working closely with ICSM & GA to ensure that ArcGIS software products support the new definitions.  Version 10.6 of ArcGIS and version 2.1 of ArcGIS Pro both include support for the new datum and projected coordinate systems (you can learn more in the Esri Australia Technical Blog)

Avoiding alignment issues mixing datums:

Web GIS, by default, displays data in the projection WGS84 Web Mercator (auxiliary sphere). When mapping data is shared to ‘Web GIS’, data is automatically reprojected ‘on-the-fly’ to this web projection in order to align with the displayed basemap and fit with the global projection. Most users do not realise that their data is being reprojected and in many instances occurs without issue.

However, while organisations are migrating to GDA2020 from GDA94 and using mixed data containing both datums, these mixed data sources will create a challenge when displayed in WGS84. The issue occurs when data is reprojected to the WGS84 Web Mercator projection.   Continue reading

ECW support for ArcGIS Pro 2.1 and ArcGIS 10.6

GDA2020 & ArcGIS

 

It is now official on the 15th of December 2017 Geoscience Australia and the Intergovernmental Committee on Survey and Mapping (ICSM) launched the new GDA2020 datum.

In support of the new Australian datum, the following tools and resources have also been released by Geoscience Australia and ICSM:

·       the ICSM GDA2020 Technical Manual;

·       additional ICSM datum modernisation Fact Sheets;

·       GDA94 to GDA2020 Transformation Grids;

·       Geoscience Australia’s GDA94 to GDA2020 Online Transformation Service; and

·       AUSGeoid2020 to convert GDA2020 ellipsoid heights to the Australian Height Datum.

So what does this mean for the ArcGIS product suite? Well from ArcGIS Pro 2.1 and ArcGIS 10.6 onwards all state, territory and national projections that incorporate the GDA2020 datum are supported.

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Alternatives to ground control in drone mapping

In my previous article I highlighted the importance of ground control for aerial drone surveying. You really can’t provide a GIS ready product unless it is coordinated by ground control. Or can you? Now I am not going to start advocating not using ground control but what if you can’t acquire ground control for your given area of interest. Are there other options?? Well yes there are. They are not as accurate as supplying surveyed ground control but they will provide a product which can be used in your system if you just need to view a mosaiced image.

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Considerations before you fly your drone for Mapping

In my position I talk to a lot of different clients about their requirements for drones. I hear of clients wanting high resolution aerial photography, elevation models, performing volumetric analysis, outputting point clouds for updating engineering designs, change monitoring and inspection scenarios. Every client has different thoughts and ideas on how they best make use of their investment. In all of these great ideas I often find that there is a great void between the understanding of what a client is looking for and their understanding of what is achievable.

Whether you purchase a helicopter, smaller quad copter or a fixed wing drone, all are delivered a flight control unit and flight management software. You’ll often though have to supply your own Smart Phone or tablet to run the software. However, it is not until you decide on exactly what you want to use the drone for, does the realisation of what is really required to achieved those results become apparent. If you are going to use it for talking single aerial pictures or video then the manual flight controller might be sufficient, however if you want to be able to use the drone for comprehensive orthomosaics or elevation modeling then there are key considerations that are required.

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GDA2020 Transformations & ArcGIS

GDA2020 logo - text under symbolIn my previous articles on GDA2020 I have highlighted some of the considerations that organisations need to have when migrating to the new datum and reasons why Australia is deploying new datum. These I hope have at least prepared you for what’s about to come.

 

In March Geoscience Australia released an interim paper

(http://www.icsm.gov.au/gda2020/InterimReleaseNoteV1.0.pdf)

regarding the definition of GDA2020 and its relationships to GDA94 and the International Terrestrial Reference Frame 2014 (ITRF2014) using similarity transformations. This provided the foundation for including the new datum into the Esri suite of products.

 

 

Shortly Geoscience Australia will release the full definitions for the GDA2020 datum and the NTv2.0 high resolution grid files for the accurate transformations from GDA94 to GDA2020. In preparation for this Esri Australia, Esri and Geoscience Australia have been working together to have the definitions and transformations available in the ArcGIS software suite. Esri is due to release an update for their ArcGIS 10.5.1 and ArcGIS Pro 2.0 suite of products. We anticipate this to be available mid to late June. These will be the first Esri products to include the GDA2020 definitions and transformations.

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