NYS ITS GIS Program Office
Geographic Information Systems Clearinghouse
New York State Digital Orthoimagery Program - Samples
Download Zips of Samples
About the Samples
The following page contains links to sample images from the Statewide Digital Orthoimagery Program. The samples are representative of the current image types and resolutions. The files are presented in the JPEG 2000 compressed format (.JP2) that is the program's standard deliverable.
A full appreciation of the utility and suitability of the imagery for your needs can best be made by downloading the sample files and performing the following evaluations. (A link to free image viewing software is also provided below.)
- Zooming in to determine the degree of interpretable ground detail with samples at various resolutions
- Comparison of the trade-off between file sizes and resolution
- Evaluation of the usefulness of the various image resolutions for interpreting ground features or conditions
- Usefulness of derivative imagery products, such as extracting a 3-band Color Infrared image from a 4-band image.
- Evaluation of the imagery for any image classification or semi-automated interpretations based on image radiometry, such as wetland delineation, soil or vegetation conditions, etc.
The following information may be helpful in evaluating the samples:
- Pixel size is expressed as a "Ground Sample Distance" or GSD, which corresponds to the dimension of a single image pixel in ground units (feet).
- The images are geo-registered to the appropriate State Plane Coordinate System zone, in Survey Feet. A .J2W file is included with each sample tile for use with ArcMap, and a .TAB file is presented with each sample tile for use with MapInfo.
- Imagery collected at 2 ft GSD has a tested spatial accuracy of +/- 8 ft (95% confidence), while imagery collected at 1 ft GSD has a tested accuracy of +/- 4 ft (95%). The half foot option has the same +/- 4 ft (95%) accuracy as the 1 ft. GSD.
- JPEG2000 compression is approximately 10:1 for 4-band imagery.
Please note that the imagery samples depict early Spring conditions to obtain leaf-off conditions. Consequently, the imagery in the samples do not have the vivid and saturated colors that can generally be expected for imagery taken in the later Spring and Summer when lawns have "greened-up" and other vegetation has begun vigorous seasonal growth. Generally speaking, imagery taken in the early spring is best for identifying the "built environment" and other man-made features that will appear in distinctly different hues than most natural features. Imagery taken in the early spring is ideally suited for determining a number of conditions in the natural environment, such as delineating wetlands, assessing soil moisture and seepage patterns, differentiating deciduous and coniferous tree species, identifying areas of "stressed" vegetation, etc.
Viewing the Samples
If you do not have GIS or other software to view the sample images on your PC, the following is a link to download a free viewer:
- ExpressView - from LizardTech, a free "easy to use image viewer"
- Questions regarding the samples can be directed to Mr. Tim Ruhren or call 518-242-5029.