Recognising the need for imagery and image-derived spatial data within the geographic information systems environment, Erdas has launched Stereo Analyst version 1.1. The package offers 3D feature extraction from stereo imagery in an easy to use PC-based environment. This alleviates the need for high-end photogrammetric solutions with their associated costs and personnel requirements.

"Stereo Analyst is Erdas' practical and affordable solution for 3D feature collection, interpretation and visualisation of stereo imagery," says Lauren Solomon, spokesperson for GIMS. "Now users can transform their 2D GIS into real-world dimensions by collecting 3D geographic information directly from imagery."

Stereo Analyst is a standalone product that easily integrates with Erdas Imagine and ArcView GIS environments. Its potential GIS applications are varied including telecommunications, forestry, state and local government planning and geology.

Stereo Analyst's sophisticated 3D data collection techniques enable users to:

* Accurately collect both 2D and 3D GIS data from a variety of image sources, without having to create a digital terrain model.

* Minimise the time and cost associated with preparing, collecting, and editing GIS data.

* Transform existing 2D GIS vectors into 3D GIS data.

* Automatically attribute spatial information to users' GIS using user-defined data dictionaries implemented through the extensive use of feature tables.

* Immediately use 3D ESRI Shapefiles in Erdas Imagine and ESRI products.

* Verify the accuracy of GIS vector layers and digital stereo models.

"In light of the complexity usually associated with Orthophoto production, Erdas has brought a well designed, user-friendly PC-based solution to the market, which integrates with its existing geographic imaging solutions," continues Solomon. "No previous photogrammetric experience is required, whilst for the experienced photogrammetrist, the tools are designed to accept data inputs from a wider variety of spatial data sources than traditional standalone photogrammetric solutions."

Wizard-based mapping software

Imagine OrthoBASE is Erdas' new Windows-based digital mapping software that simplifies complex photogrammetric procedures. The product's clean design, wizard-based tools and automated processes dramatically reduce the initial learning curve, as well as the time and money spent geocorrecting and orthorectifying images. Imagine OrthoBASE eliminates the current limitations of complex, difficult-to-learn packages while providing rigorous and precise computations and results.

Some of the main capabilities of OrthoBASE are as follows:

* Rigorous sensor modelling of various camera and satellite sensors (SPOT, IRS-1C) as well as generic models for push-broom sensors.

* Supports aerial, oblique and terrestrial (ground-based) imagery.

* Semi-automated interior orientation.

* Automatic tie point collection.

* Ground control point measurement.

* Aerial triangulation.

* Self-calibrating bundle adjustment allows for the use of 35 mm, digital cameras, video cameras and archival photography.

* Sophisticated automatic error checking models.

* Block adjustment of sensor models resulting in a better fit between adjacent images and better overall accuracy with less control points.

* Orthorectification of images within a block based on an existing digital elevation model.

In the provision of a complete solution, OrthoBASE can supply stereo pair data for use in Stereo Analyst in the extraction of elevation information (buildings heights, contours values, etc). The elevation information collected can then be used in the generation of a digital elevation model, which when loaded into OrthoBASE can be used to generate a digital orthophoto.

3D analysis tool assists decision-making

In the field of geographic imaging, the ability to visualise spatial data within a three-dimensional environment, adds significant value to the decision making process. Erdas has developed a 3D environment that is integrated within the Imagine geographic imaging suite and adds comprehensive visualisation functionality to the already rich imaging toolset.

Imagine VirtualGIS is a powerful, three-dimensional visual analysis tool that offers GIS functions and capabilities in a 3D environment.

"It takes users' projects to a new level through interactive 3D modelling, intervisibility/threat analysis, VRML 2.0 support for creating 3D web content, realtime anaglyph stereo (no need for specialised graphics cards) and the generation of high-resolution 3D images for printing," says Solomon.

The functionality of Imagine VirtualGIS enables users to:

* Extend the Geographic Imaging functions of Erdas Imagine, within a realtime, 3D environment.

* Experience realtime, 3D navigation through a large database of image, map and attribute data.

* Geographically link 3D and 2D views of the same location.

* Apply enhancement functions and spatial filters within the 3D environment.

* Query attributes of image and vector data interactively in 3D.

* Fly through a database using predefined flight paths or using mouse controls.

* Output to standard movie formats and VRML.

* Calculate visible and obscured locations for a particular viewing location.

"This functionality is essential in many environmental, telecommunication, and defence applications," Solomon concludes.

Geographic Information Management Systems (GIMS)

(011) 315 0390

sales@gims.com

Footnote: All imagery provided courtesy of Golden State Aerial Surveys and City of San Louis Obispo, CA.