Texas Water Development Board (TWDB), Texas General Land Office (GLO) 2017 1.0 All digital data COS Sanborn N/A This metadata record describes all Orthoimagery derived products data for the 2017 Texas Coastal project covering approximately 64 miles of upper, middle, and lower Texas coast. The coastal areas include the Gult-facing shoreline in Galveston County, City of Galveston, Jamaica Beach, Village of Surfside, Cameron County, South Padre Island, Port Aransas (up to end of bollards), Corupus Christi Seawall (south of Packery Channel along the legth of the Gulf-facing seawall). This data is a collection of orthorectified aerial imagery. The orthorectified imagery was delivered in uncompressed tiled 8-bit format (4band RGBNIR). Tiled and a project-wide mosaic (JP2) were also delivered at 20:1 ratios. The data was produced at the request of the Texas General Land Office by The Sanborn Map Company of Colorado Springs. This orthorectified imagery has a pixel resolution of 15cm. The data was flown August 12th and September 9th of 2017 using a UltraCam Eagle camera. This data is within the UTM Zones 15N. Datum of NAD83 (2011) and is in Meters. Rectified orthoimagery for the use of the Texas Water Development Board participants. This orthoimagery project is originally meant to map the costal vegetation and review beach use. An orthoimage is useful as a layer of any geographic information system (GIS). It can function as a cartographic base for displaying, generating, and modifying associated digital planimetric data. Other applications include environmental impact assessments, disaster management, emergency evacuation planning, flood analysis, soil erosion assessment, facility management, ground-water and watershed analysis, right of way and road alignment, transportation network inventory and analysis, preliminary design studies, vegetation classification detection of physical features or attributes not possible at ground level, and a myriad of additional applications. Project Projection, Datums and Units. Projection - UTM Zones 15N. Horizontal datum - North American Datum of 1983 (2011). Vertical datum - North American Vertical Datum of 1988 (NAVD88) using the latest geoid (Geoid12b) for converting ellipsoidal heights to orthometric heights. Units - meters en 20170812 20170909 ground condition Complete Unknown -97.39798412 -93.83805837 29.68936031 26.06901253 Texas Coastline 2017 Aerial Imagery Orthoimagery Ortho Orthophotography Imagery Photography Vexcel UltraCam Eagle GeoTIFF Texas Coastline Texas Coastline United States none 2017 This data may be used by the requested party for stated purposes and should not be re-distributed. This data is for planning purposes only and should not be used for legal or cadastral purposes. Any conclusions drawn from analysis of this information are not the responsibility of Sanborn Map Company. Users should be aware that temporal changes may have occurred since this dataset was collected and some parts of this dataset may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations. GLO & TWDB Carly Vaughn mailing address

1700 N. Congress

Austin TX 78701 U.S.A. (877) 228-5740 8:00 AM - 5:00 PM Microsoft Windows 7; ESRI ArcCatalog 9.3.1.1850 & Esri ArcGIS 10.2.1.3549 unknown Unclassified unknown GeoTIFF, JP2, SHP, XML The digital imagery for each acquisition sortie is differentially rectified to produce orthophotography at a resolution of 15cm. Once the imagery has passed quality control review, final radiometric adjustments are performed to create a uniform overall appearance. The process is overseen by a ASPRS Certified Photogrammetrist (CP). The CP overseeing production at Sanborn is Doug Zehr. The ortho image tiles are checked for missing pixels, gaps, overlaps and other anomalies generally associated with digital orthophoto products. Any discrepancies in the ortho tiles are resolved through the use of proprietary and industry editing tools. Once the images are copied to the deliverable media they are further checked for naming, image completeness, and ability to be loaded in ArcMap. Horizontal accuracy is based on ground control and digital elevation model data provided by Sanborn Map Company that was used in the production of the digital orthoimagery. 30cm Specification requires that data meet a 30cm RMSE requirement. Points were surveyed and compared to location within the orthophoto and found meet this specification. N/A 0.0 Orthoimagery does not have inherent vertical accuracy. Aerial Images The Sanborn Mapping Company, Inc. 2017 remote-sensing image 20170812 20170909 ground condition IMG The aerial imagery was captured with an Vexcel UltraCam Eagle digital camera. The UC Eagle is a full frame digital camera system. The aerial images are used to AT the project and the production of orthophotos. New digital, color aerial imagery of the site is acquired using Vexcel UC Eagle aerial camera system. Airborne GPS/IMU data is recorded along with the imagery. 20170812 The digital aerial imagery was transferred from the camera to a Mass Storage Unit (MSU) and shipped to Sanborn's main facility in Colorado Springs. Once downloaded, Data is processed via software from the raw camera format to a 4-band unsharpened color image and a pan image. An application is executed that outputs the mid-exposure pulse for each image. At this point a POS file is processed photo files as input to the Aerial Triangulation process. Raw camera data files are archived on LTO3 tapes. The imagery is processed using processing software to create a 4-band multispectural (RGBN) format. The images are archived (on LTO3 tapes) and removed from system when orthophotography production has been completed. 20170812 Softcopy (Digital) Aerotriangulation: This task involved the densification of ground control points, measurement of photo coordinates, computation and block adjustment to solve for exterior orientation parameters of individual photographs necessary for ortho-rectification. New ground control locations surveyed by the Sanborn map company; a combination of photo-identical points and targeted points were used. The ground control points were measured in a fully digital environment using softcopy stereoplotters and tie point and passpoints automatically generated. Analytical aerotriangulation computations and adjustment were done using Inpho Match-AT software, which is capable of performing bundle block adjustments using a rigorous least squares analysis, and possesses error detection and removal facilities. Systematic error corrections for lens distortion, earth curvature, and atmospheric refraction. State-of-the-art software with highly sophisticated error-detection routines was used to perform the computation and bundle block adjustment. Trained aerial triangulation specialist analyzed both numerical printouts and graphical error vector output display to detect gaps or holes in the block due to missing tie points, pass points or ground control. 201709 The digital elevation model (DEM) data was provided by Sanborn, for the purpose of rectification of the imagery. Autocorrelation techniques were utilized to create them DEM. Where this was not possible, NED was extracted and used as the elevation model. 201709 Orthorectification: This task involved orthorectification of the raw digital raster images that were created from processing of UltraCam Eagle digital camera data. A number of image processing techniques were used to maximize the quality of the deliverable images. Digital orthoimagery was created by draping the un-rectified raster images over their corresponding digital terrain models. All relief displacement was removed from the raw image files at ground level on a pixel-by-pixel basis using mathamatical pixel manipulation and seams, yielding a set of orthorectified digital photo images. Mosaicking was performed to ensure a perfect edge match between all orthoimage tiles. Seam lines were generated automatically and manually manipulated where necessary to ensure that no image flaws result from seam lines passing through tall structures. Seamline calculations bring in radiometric values of the pixels that are used first and then the terrain is brought into the equation. The software uses the radiometric values to go around cars and buildings the best it can. If the software detects a substantial change in the surface (like steep hills to cliffs), the software will try to compensate with another image, to avoid smearing of the imagery. If the seams would not compensate for the surface change, it would create a smear or the hillside would be more stretched than it should be. There will be on occasion patches of seams hiding these terrain changes. All orthoimagery tiles were generated butt joints, no overlaps nor gaps. Radiometric adjustment was performed to balance and match color tones, brightness and contrast of the imagery over the whole project. Color orthoimagery were produced 8-bit per channel, resulting in 8-bit RGBN, .tif/.tfw format with a pixel size of 0.15m. Ortho tiles were generated according to the pre-approved orthoimagery tile layout. 201709 Quality Control All orthophoto tiles were thoroughly inspected according to Sanborn QA/QC quality control procedures. Comprehensive visual inspection included looking for mosaicking, image smearing and color balancing across the entire project. The process is overseen by a ASPRS Certified Photogrammetrist. The CP Overseeing production at Sanborn is Doug Zehr. 201709 Dataset moved. 201709 Metadata updated/imported 201709 0 N/A N/A Digital orthoimagery does not contain inherent attribution. Raster Pixel 4 8 GeoTIFF Pixel Codes Upper Left None 0.15 0.15 255 North American Datum of 1983 (2011) Geodetic Reference System 80 6378137.000000 298.257222101004 GCS_North_American_1983_2011 NAD_1983_2011_UTM_Zones_15N Lambert Conformal Conic 32.1333333333 33.9666666666 -98.5 31.6666666666 1968500 6561666.6666667 coordinate pair 0.01 0.01 meters Carly Vaughn GLO & TWDB mailing address

1700 N. Congress

Austin TX 78701 U.S.A. (877) 228-5740 8:00 AM - 5:00 PM Texas Coastline 2017 The digital data have been tested and their documentation carefully reviewed. However, the Client and its representatives make no warranty or representation, either expressed or implied, with respect to the digital data and their documentation, their quality, performance, merchantability, or fitness for a particular purpose. The digital data are distributed on "as is" basis, and the user assumes all risk to their quality, the results obtained from their use, and the performance of the data. This disclaimer of warranty is exclusive and in lieu of all others, oral or written, express or implied. No agent or employee is authorized to make any modification, extension, or addition to this warranty. GeoTIFF N/A unknown 1 - 1/2 inch hard drive GeoTIFF unknown TWDB unknown 2017 20170919 Bridget Marcotte Sanborn Map Co Project Manager mailing address

1935 Jamboree Dr

Colorado Springs CO 80920 U.S.A.

Suite 100

719.244.2311 bmarcotte@sanborn.com 8:00 AM - 5:00 PM FGDC CSDGM FGDC-STD-001-1998 20170919 0 TRUE 20170927 13470700 {8DE3DE1B-30AB-48D1-9B5B-D8574399589A} Local Area Network Color orthophotos are comprised of pixels. Each pixel is assigned a value of 0 to 255. That number will refer to a color look-up table which contains red, green and blue (RGB) values, each from 0 to 255, for that pixel within the image. None 20170927