In recent years

there have been many catastrophic disasters occurred in China and other countries

which has caused great losses of lives and assets.Spatial information techniques

including

are playing more and more important roles in disaster mitigation.An earthquake

measured 8.0 on the Richter scale

struck Wenchuan County

Sichuan Province at 14∶28 on May 12

2008

and has resulted in a series of catastrophes.Different departments involved in disaster mitigation have used spatial information techniques to provide decision-making support and contributed a lot to the earthquake relief.Besides the prompt response to the disaster

the amount of spatial information collected in this earthquake and the number of specialists in related fields involved in the disaster mitigation are unprecedented.The rapid response action

as a classic case

can provide a very helpful reference and example for future disaster mitigation with the help of spatial information techniques.Firstly

the requirements of spatial information techniques in rapid response to the earthquake are identified

including airborne/space-borne optical and SAR RS data in high spatio-temporal resolution

geometric positioning in high accuracy without GCPs or few GCPs

real time/near-real time data processing

and well prepared spatial data of infrastructures in earthquake area.Disaster mitigation can be classified into three main phases

which focus respectively on rescue of people buried under the ruins

monitoring of the secondary disasters such as land slides

mud flows and quake lakes

and disaster reconstruction planning.In such different phases

spatial information techniques may play different roles.To acquire sufficient space resources

the International Charter "Space and Major Disasters" is activated by its authorized user NDRCC to obtain foreign satellites data

while the national resource satellites Beijing-1 and CBERS are being operated continuously.More than 130 scenes of satellite images are received through the Charter.On the other hand

the advanced airborne sensors such as Leica ADS40

Z/I Imaging DMC

and SWDC-4 are involved to monitor the detailed information about the earthquake.Leica ADS40 has been most widely used in damage information extraction for its convenient processing method and integrated operation environment.SWDC-4

the best airborne digital mapping camera made in China

has also been running stably during the disaster relief.The airborne SAR sensors have shown their flexibility to the weather condition and achieved most volumes of data in its average 11 hours flight per day.However

its data processing speed is in urgent need of improvement.Secondly

the rapid processing technique for different RS data is the key step in the course of disaster rapid response.The satellite ortho-rectified method based on RPC model showed a good accuracy in the satellite RS image processing only with few GCPs

though the disaster area has extremely diversified terrains and was heavily changed by the earthquake.As for the airborne RS data processing

the rapid image matching and mosaic methods used in DPGrid successfully solved the problem of irregular flight line and great rolling stereo image pairs.The image dodging technique can enhance the visibility and interpretation effect of mosaic results of airborne images.Geododging

a software package of image dodging developed by Wuhan University has presented good performance.Thirdly

the damage information extraction and secondary disaster monitoring are two main applications of spatial information techniques in the earthquake rapid response.Two advanced image change detection techniques have been used.One is change detection with images from different sensors.And the other is mono-images change detection according to the spatial shape information based on the object-oriented segmentation.Both can remedy the deficiency of image source and improve the monitoring speed.The optical image data and airborne LIDAR data are both used in the secondary disaster monitoring.Three procedures as watershed segmentation

runoff prediction by distributed hydrologic models

and storage calculation of Quake Lake are integrated to monitor the dangerous conditions of the Quake Lake dam.Finally some conclusions and suggestions are proposed to direct future disaster rapid response.