Sensor Evaluation: Resolution Comparison, 30 - 1000 m

In this 2x zoom of a 30-m Landsat TM image of the outskirts of Stockton, California, a few agricultural fields can be seen in various stages of canopy development and may be different crops as well, and fields that are probably bare are darker blue-green. The image is dominated by residential developments. The community in the lower right is mostly red, indicating it has established trees similar to the community in the upper left of the 10-m image to the right. The residential areas at the edge of town have only a hint of vegetation (red), so are probably new developments.

Resampled to 10-m resolution, this ARTIS image shows clouds in the upper middle and an urban or industrial region in the upper right. Residential road patterns can also be seen. Agricultural field patterns are difficult to see and the woods in the lower middle is a reddish-dark patch with some variation within it.

At 30 m spatial resolution, a grid pattern of agricultural fields can be seen in various colors, from the bright red of fields with full canopy development, to copper and brass colored fields with little canopy, to dark blue-green of bare fields, and the very dark blue-green of wet or burned fields. The residential areas are a maze of twisting roads with various amounts of vegetative red.	In larger fields variations can still be seen at 60-m resolution, but residential areas are speckled with more or less dense vegetation. With the increased area, wavy, dark curves of rivers are visible.
Increasing the area further with 120-m resolution, the rivers can be seen to connect a number of lakes. At this scale the residential areas of Stockton are fairly uniform regions of color and the agricultural fields are smalls color chips. In the lower left are the valleys and grooves on bare slopes of the mountains.	At 250-m resolution the fields are blending together and only the larger mountain valleys can be easily seen. Roads and small rivers have also faded away. The cities of the East Bay are a cyan and red patches, while the Palo Alto-Atherton area has more tree canopy. Also visible is the San Francisco Bay, with its green-color salt evaporation ponds at the South end.
At 500-m resolution the coastal forests, mountains, and cities are speckled, with only large distinct areas vibible. Golden Gate Park and the Presidio can be seen at the tip of the SF Peninsula. The small cyan point in the Bay just off the tip of the Peninsula is Alcatraz, and the larger cyan island is Treasure Island.	At 1000-m resolution the dense urban areas are cyan-white strips and few details can be seen.
This is the same image as above right: a 30-m resolution TM image resampled to 1000 m. As a color-infrared image, it uses three of the TM channels: green, red, and near-infrared.	The above image is the same area (different date) as recorded by AVHRR at 1.1-km spatial resolution. However, AVHRR has a red, near-infrared, and three thermal channels, so it is a red-nearinfrared (RIR) and thermal infrared (TIR) sensor, not a multispectral sensor like TM. This image is actually only two bands. While the vegetation in the TM image has an orange tint, the AVHRR image shows only red vegetation. Major waterbodies have also been removed from the AVHRR image because the data were obtained from the USGS Global 1-km Land DAAC, and the water bodies are removed as part of their processing.