This tile is part of a collection of color infrared orthophotos covering the 2007 City of Madison, WI project area. An orthophoto is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthophotography combines the image characteristics of a photograph with the geometric qualities of a map. The imagery was captured at 12-bit radiometric resolution and converted to 8-bit radiometric resolution during post processing. The imagery was obtained and processed by all digital means beginning with data acquisition using a Z/I Imaging Digital Mapping Camera (DMC). To create color infrared imagery, the acquired blue band is discarded and the near infrared band is included in the final image in its stead. The orthophotos are available in GeoTIFF and MrSID format.
The Project will provide updated ortho imagery to City of Madison’s existing digital ortho imagery catalog that dates back to 1997. This imagery will enhance the City’s enterprise GIS and directly support parcel management, asset management, community planning, public works, remote sensing and other GIS applications. The acquisition of current ortho imagery will also be very valuable to other City departments such as Police, Fire, Parks, Forestry, Health, and Assessor consequently making the Project a great resource for City of Madison at large.
This dataset was developed in conjunction with the development of a larger 0.3 pixel resolution color orthophotography dataset for the USGS as part of the Urban Areas 133 program. This dataset was rectified using LiDAR data acquired over Madison, WI in 2005.
Date of source imagery acquisition.
REQUIRED: Restrictions and legal prerequisites for using the data set after access is granted.
1802 Pankratz Street
Orthophotography was generated to meet ASPRS Class 1 for 1"=100' scale mapping.
Ground control consisted of photo identifiable surveyed points. The imagery was collected using a Z/I Imaging Digital Mapping Camera (DMC). Image quality was verified during the post flight review phase. Factors considered during this review included but were not limited to the presence of smoke and/or cloud cover, contrails, light conditions, snow presence and sun glint. The triangulated strips were rectified with a surface created from a LiDAR mission that took place in 2005. The red, green and near infrared bands were combined to generate a final color infrared orthophoto. The DMC collects twelve bit image data which requires radiometric adjustment for output in standard eight bit image channels. Converting to eight bit results in a reduction of the color range from 4096 to 256 - thus loss of radiometric detail is inevitable. The extra dynamic range of the sensor permits greater object differentiation in shadows and in bright areas. The sixteen bit dynamic range permitted the imagery to be more effectively color balanced than is possible with eight bit imagery. This was accomplished by performing tonal enhancements immediately prior to the reduction from sixteen bit to eight bit data. In addition to color balancing these eight bit images were adjusted to create seamless imagery to the highest extent practically achievable. The imagery was mosaicked using a combination of automated and manual seamlines generation. Project specified tiles were extracted from the mosaic. Final image tiles were reviewed for artifacts and anomalies and adjusted as part of quality control procedures. Adjacent images are compared for consistency in overlap regions. The images are reviewed for rectification problems such as bridge displacements caused by the underlying digital elevation model. When necessary, local corrections to the imagery were performed to minimize such effects.
1802 Pankratz Street
Metadata imported.
1802 Pankratz Street