Sunday, 9 August 2009

Satellite Imagery & Elevation Data for Malaysian Road Engineers

Our road engineers have always been an early adopter of new mapping products in the route selection and preliminary design stage of their highway construction process. On August 8, 2009, I was honoured in being invited by the Road Engineering Association Malaysia (REAM) to deliver a talk during their "Library Talk" session.

A 60-minute presentation on the above caption and interaction with the engineers was definitely a satisfying experience, even though it is somewhat uncommon thing for me to do on a Saturday morning. The entire proceeding was video-taped and I was told it will be uploaded to YouTube soon. I will link it to this blog for your viewing pleasure as and when it becomes available.

A summary of the talk is as follows:

From the line maps produced by analogue photogrammetric means in the early '80s to the fully digital line maps produced by analytical plotters in the late '80s, road engineers have followed closely the technology highway to ensure that the highways they planned and designed in Malaysia are done in an efficient manner.

Digital aerial orthophoto maps of the '90s were the first examples of digital images known to the road engineering fraternity. In 2000, the 1m high-resolution satellite IKONOS image became available. Over the years, it establishes itself as the "mainstream" data for route selection and preliminary design of proposed highways in Malaysia. There is no looking back after that.

With the introduction of new Geoeye1 0.5m resolution and RMSE 3m satellite images, road engineers can now reap the benefits of detail and accuracy that space technology has to offer. For the moment, the leap in accuracy from 25m (of IKONOS) to 3m (of Geoeye1) has definitely quench the current thirst for accurate planning data.

In contrast with the progress made in image resolution and geometric accuracy of satellite-based images, little has changed in the availability of uniform and complete elevation data in Malaysia. The only "nationwide" elevation data available in this country was the contour lines derived from 1:50,000 scaled topo sheets produced by the national mapping agency since the '80s. The NEXTMap Malaysia IFSAR elevation data set is now ready to be "the data of choice" over the next few years.

The combination of Geoeye1 satellite image and IFSAR elevation data (mixing better detail with accuracy) now caters for most preliminary planning and design requirements of road projects. Who knows what technology can bring over the coming years. 3D terrain visualization is the logical next step in the merging of the two different sets of data for us (imagine having the whole project site in 3D in front of you, giving a better understanding and presentation of the ground condition in the comfort of an office environment is something you road engineers had wanted all this while, right?). Road design and development is getting more easy and affordable, all thanks to the much improved availability of image and elevation data.

Written by: Kong Hin Yew

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