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Imagery Comparison
Excerpt from the Draft Report: Imagery for Creating/Updating Land Cover/Land Use Data in Michigan. Submitted to the Michigan State University Land Policy Program under the Special Projects Grant: Methodology for Land Use and Land Cover Mapping: Techniques and Data Deliverables for a Statewide Approach (2004). Authors: Ms. Jessica Moy, Dr. W. Dennis Hudson, Mr. Robert Goodwin, and Ms. Sarah AcMoody, MSU Remote Sensing and GIS Research and Outreach Services (RS&GIS)
RS&GIS has completed a controlled comparison of several image types designed to evaluate film types (or satellite band selection), scale/resolution, level of interpretability, and acquisition cost for updating land cover/land use maps. Several imagery sets were tested - black and white, natural color, and color infrared high resolution aerial imagery, and 1 to 4 meter resolution satellite imagery. While the low resolution satellite imagery was deemed too coarse to provide the needed level of interpretability, the remaining image sets produced similar results. A detailed description of the procedures and results are available in the final report (Goodwin and Hudson, 2002, Comparison of Air Photo and Satellite Image Sources for Updating Land Cover and Land Use Maps. Center for Remote Sensing and GIS, Michigan State University, East Lansing, Michigan).
Through the Special Projects Grant, awarded by the Michigan State University Land Policy Program, this imagery research has been furthered to include new satellite resources. Preliminary results are found in the table below.
| Issue |
Aerial Imagery |
High Resolution Satellite
(Quickbird or IKONOS) |
Coarse Resolution Satellite
(SPOT) |
| Resolution |
Varies
Recommend 1-meter or better |
2.44 - 4.0 meter Multi-spectral;
0.61- 1.0 meter B&W |
5.0 m Multi-spectral;
2.5 meter B&W |
| Color |
Varies
Recommend CIR |
Varies
Recommended CIR |
Varies
Recommended CIR |
| Acquisition |
Statewide, Cloud-free coverage - 1 yr
Statewide, Cloud-free, single season - 2 yr |
Estimated figures: Statewide, Cloud-free coverage - 3 + years;
Statewide, Cloud-free, single season - 8 + yrs |
Estimated figures: Statewide, Cloud-free coverage - 1 + years;
Statewide, Cloud-free, single season - 2 + yrs |
| Ownership |
Generally owned by the client |
Restrictive Licensing based on organization (limited # of users or limited # of organizations), 30 - 35 % uplift for multiple organizations |
Restrictive Licensing based on organization (limited # of users or limited # of organizations) |
| Pros |
Quick turnaround, High Resolution, Short collection time (1-2 years), Relatively inexpensive, Date continuity. |
Good Resolution, digital geo-referenced deliverables, multiple products (pan, multi-spectral) |
Relatively inexpensive, digital geo-referenced deliverables, multiple products (pan, multi-spectral) |
| Cons |
Must be converted to digital and geo-referenced |
Expensive (3 - 5 X aerial photography with standard tasking), Long collection time for large areas (8 + years for entire state of Michigan), no date continuity, allows 10 % cloud cover |
Poor resolution limits interpretability, allows cloud cover |
Imagery Recommendations:
Based upon the experience and research performed by RS&GIS staff, the following is a list of recommended criteria for imagery used to update/create land cover/land use data:
| Issue |
Recommendation |
Rationale/Discussion |
| Type |
Air Photo |
High resolution satellite imagery is appropriate for the project, however, cost and acquisition time are prohibitive |
| Color |
Color Infrared or Natural Color |
CIR would be best choice, especially if using Leaf-On (Summer) imagery |
| Resolution |
1-Meter or finer pixel resolution |
Coarser resolutions prohibit detailed interpretability |
| Format |
Digital, Ortho-rectified imagery mosaics |
- Horizontal accuracy to meet 1:12,000 National Map Accuracy Standards (consistent with current state of Michigan data standards)
- Color-balanced, matched, and tiled
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| Season |
- Entire state should be imaged in 1 to 2 years
- Leaf-Off
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- Same season imagery is crucial for data consistency
- Leaf-Off (Spring) imagery is flown within an approximate 6 week window in Michigan
- Leaf-On imagery is acceptable, however, urban residential is often under-represented due to tree canopy
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