NGATE, an image processing innovation developed by BAE Systems, uses a hybrid matching process to create precise elevation data for 3-D terrain and surface models. Its unique combination of image matching techniques offer clear improvements over earlier digital photogrammetric mapping procedures for generating elevation data from imagery.
NGATE is particularly useful for mapping urban areas, large geographic landscapes, mountainous or rough terrain, and areas with little contrast, such as road surfaces on large scale imagery and vast deserts. It is extremely accurate when compared to other automated algorithms, can decrease manual editing time by more than 30%, and streamlines production workflows.
Please note: NGATE is not available for purchase as a separate module with SOCET GXP®. In SOCET GXP v3.0+, both ATE and NGATE are included in the Automatic Terrain Generation (ATG) module.
NGATE and ATE – which one should I use?
Both NGATE and ATE are used to create digital terrain models (DTM). In SOCET GXP the output format of the DTM is a grid, which is a two-dimensional array of elevation points called posts. The array of posts is always aligned north, south, east, and west with the coordinate system.
NGATE is significantly different from ATE. ATE performs image correlation on each post. NGATE performs image correlation and edge-matching on each image pixel. Users control ATE speed by using a large post spacing to reduce the number of posts. NGATE speed is not dependent on post spacing or number of posts. Users control NGATE speed by stopping NGATE at a different minification level using different Precision/Speed options.
The most significant advantage of using NGATE over ATE is for difficult areas such as large-scale imagery in urban areas. ATE is not effective for distinguishing buildings from the ground. Therefore, the DTM climbs up over building roofs. NGATE DTM quality in those difficult areas is far better than those from ATE. As a result, NGATE can significantly reduce DTM editing time.
In terms of DTM accuracy, NGATE almost always produces more accurate DTMs than ATE. If speed is important to DTM production, users should set the NGATE Precision/Speed option to Medium/Medium. With this setting, NGATE can generate a DTM faster than ATE with slightly better accuracy. If the desired product is an accurate and dense DTM, NGATE always performs better than ATE.