What is orthophotography?

Orthophotos are a stereo pair of aerial photographs mathematically and optically corrected to eliminate distortion caused by the curvature of the Earth and the curvature of the camera lens, but still have the readability of an aerial photograph. The main difference between orthophotos and aerial photos is that measurements can be done on orthophotos.

When were the photos taken?

The entire County was re-flown in Spring 2008 as part of a regional partnership that included the Southeast Michigan Council of Governments (SEMCOG), United States Geologic Survey (USGS), and several SEMCOG counties: Livingston County, Macomb County, & Oakland County.  The imagery should be available before the end of the year.

The County's first orthophotography project was completed in March 2000 during the vegetation leaf-off period. Images covering the entire county are in true color.  The entire county was updated in Spring 2005 with 6" resolution imagery captured for the entire SEMCOG region.

The County flew the southeast portion (Brighton, Genoa, Green Oak, & Hamburg Townships) of the County on April 10, 2002. The County updated the orthos in the northeast quadrant of the County (Deerfield, Tyrone, Hartland, Oceola Townships) in 2003.

What is the resolution of the imagery?

For the County's first ortho project (2000), the county was flown at two scales: 1”=833’ in urban or suburban areas and 1”=1333’ in rural/suburban areas. The 1”=833’ scale was used to produce a Digital Orthophotography (DOP) mosaic with approximately 6” resolution imagery. The 1”=1333’ scale was used to produce a DOP mosaic with approximately 9” resolution imagery. Subsequent updates (2002, 2003, 2005) were flown at only one scale and all images for these years have 6” pixel resolution.  The 2008 imagery has 12" pixel resolution.

What is the file size of the digital orthophotography?

Statistics for the first ortho project (2000) include: File size of the uncompressed TIFF is approximately 105mb for the 6” resolution imagery and 187mb for the 9” resolution imagery. There are approximately 972 6-inch resolution images and approximately 255 9-inch resolution images. The images needed to cover the entire county are approximately 143 gigabytes. The size of the MrSID images varies by number of tiles included in each mosaic and the resolution of the original TIFF images. A ¼ township section composed of 6” resolution imagery ranges from approximately 141mb to 194mb. A ¼ township section composed of 9” resolution imagery ranges from approximately 64mb to 95mb.

The images received from the 2002, 2003 and 2005 ortho updates have even larger file sizes.  The most current imagery acquired in 2005 is approximately 350 gigabytes for the entire county.  A compressed version of the orthophotography is also available in MrSID format.  The file size for the MrSID mosaics generated for each township are about 1GB per township.

When will new photos be taken?

The entire County was re-flown in Spring 2008 as part of a regional partnership that included the Southeast Michigan Council of Governments (SEMCOG), United States Geologic Survey (USGS), and several SEMCOG counties: Livingston County, Macomb County, & Oakland County.  The imagery should be available before the end of the year.

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What data is found in the Roads layer?

Road names can be auto-labeled or can be added to a map as annotation. The road names were verified in 2004 and the GIS Roads layer contains the correct road name for the majority of streets in the County. The roads file also includes address ranges for every segment in the county.  Additionally, codes required for maintenance of the Qualified Voter File have been added to the road centerline layer.

E911 Central Dispatch uses the road names and address ranges as part of the Computer Aided Dispatch system. The County Clerk and local Clerks also utilize the road centerline data to assist with maintaining the Qualified Voter File to ensure each voter is placed in the proper precinct, school district, zip code, etc.   The roads are updated at the end of each month.

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What is the accuracy of the Parcel layer?

Generally, the parcel lines are within 5-10 feet. However, we know certain areas need further investigation, which will occur as we maintain the parcel layer. If you think the parcel lines are not accurate, please contact the Tax Mapping Specialist and provide any additional deeds, surveys, or other information that may help us map your parcel.

How did you map all the parcels in the County?

We mapped the legal description listed in the tax roll. Each parcel or subdivision was entered in AutoCAD. Then, all parcels were put together like a puzzle to create the data you view through the GIS. The subdivisions were inserted into the township-wide drawing first because they are platted/surveyed and (most likely) have a higher spatial accuracy. Next, the parcels with Metes & Bounds descriptions were inserted. Finally, any aliquot description (NE¼-NE¼-etc) or description referencing landmarks were entered.

What information can you obtain from the Parcel layer?

Each parcel has long tax id number and short tax id number (which is easier to use for labeling). The parcel polygons have been linked to the assessment database to display owner information, addresses, assessment values, etc. The GIS_ACRES field contains the acreage calculated by the GIS; it may not match the acreage included in the legal description. Along with the parcel lines, subdivision polygons with names and block numbers are also available. All parcel-related data layers are updated on a daily basis.

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What do Elevation Contours show?

The 5' Contours are derived from the Digital Elevation Model (DEM), which was created for the 2000 orthophotography flight. The orthophotography vendor generated the contours in the eastern half of the County. The contours for the western half of the County were generated in-house using the ESRI 3D Analyst Extension. The accuracy of the contours has never been verified. Contours can be used to provide a general topography of the land. If contour lines are close together, then a slope or ridge exists in that location. Contour lines also point upstream so users can determine the general drainage pattern of the area.

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What features are included in the Hydrology dataset?

Lakes, rivers, & open drains are included in the dataset. These features were digitized from the orthophotography. The Lakes file includes all open water sources. The Rivers file includes all rivers, streams, creeks, & open drains. Names of the County Drains were obtained from maps provided by the Drain Commissioner’s Office; no tile drains have been included in the hydrology dataset. Private drains have a unique naming scheme composed of the township and section where the drains are located.

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What does the Wetlands data indicate?

The Wetlands layer is a digital version of the National Wetlands Inventory. These data were compiled in 1971 and have not been updated recently. The classes indicate the type of vegetation potentially found in that location.

Does the presence of wetlands on my property mean that I cannot build?

Not necessarily. The Michigan Department of Environmental Quality regulates wetlands that meet certain criteria. Contact the MDEQ at 517-241-1515 or visit the Wetlands Protection portion of the MDEQ website http://www.michigan.gov/deq/0,1607,7-135-3313_3687-10801--,00.html to obtain additional information.

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What is a floodplain?

A floodplain is an area adjacent to a river, lake or stream that will be inundated by water when a flood occurs. Every river, lake or stream has a floodplain associated with it.

What is the 100-year floodplain?

The 100-year floodplain is the land adjacent to a river, lake or stream that will be inundated by water during a flood which has a 1% chance of occurring of being exceeded during any given year. Each year, there is a 1% chance of a 100-year flood event. The 100-year flood may occur several years in a row or it may occur very infrequently. If you live within the 100-year floodplain, we do not know when the 1% chance flood will occur, but at some point in time, it will occur.

Is my property in a floodplain?

The Federal Emergency Management Agency (FEMA) creates maps showing the 100-year floodplain for communities that participate in the National Flood Insurance Program. Not all communities choose to participate in the program so floodplain maps are not available for each local unit in Livingston County.

As of January 2007, these communities in Livingston County have floodplain maps: Handy, Fowlerville, Howell City, Hartland, Brighton City, Putnam, Pinckney, Hamburg, and Green Oak. Flood Insurance Rate Maps published by FEMA area available online, or you can call the FEMA help line at 1-866-336-2627. You can also contact your community (City, Village, Township, County), your local library, or the MDEQ Land and Water Management Division.

Why am I required to buy flood insurance?

Under the National Flood Insurance Program Reform Act, if a building securing a loan is located within a federally identified 100-year floodplain and the lender is federally regulated, supervised or insured, flood insurance must be required as a condition of the loan. Under the Act, if the lender makes a loan on a structure that is in the 100-year floodplain and does not require the flood insurance, they will be subject to fines.

How can I prove I am not in the floodplain so I do not need to purchase flood insurance?

The first thing you need to do is determine if your house is in the floodplain. If only a portion of your property is in the floodplain, but the house is not with in the floodplain, there are no federal requirements for the purchase of flood insurance. Contact your lender to be sure they have located your property correctly. If the house is within the floodplain on the Flood Insurance Rate Map, the only way to remove the flood insurance purchase requirement is to apply to FEMA for a letter of map amendment (LOMA). A LOMA requires that the property owner submit elevation information that demonstrates that the structure is above the 100-year flood elevation. The elevation certificate and the LOMA can be downloaded from FEMA’s website. These forms are also available from the local DEQ office or the Lansing DEQ office at 517-373-1170.

How often does FEMA update the Flood Insurance maps?

In 2005, FEMA began a process to create new and/or update flood hazard data in Livingston County’s three major watersheds: Huron River Watershed, Red Cedar Watershed, & the Shiawassee River Watershed.   The new Flood Insurance Rate Maps should be available in 2007.

Contact the Department of Environmental Quality if you have additional questions about floodplains or flood insurance. Website: www.michigan.gov/deq then click on the Water Management link to access other web pages that provide additional details. Phone: 517-335-3181

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How much does it cost for a hard copy printout?

Livingston County GIS offers a number of layers, which can be combined to create a custom map. The cost varies by the layer requested and the paper size selected (view our Paper Map Order Form for current prices).

How do I order a map?

The maps can be purchased in hard copy or digital format by visiting the GIS office located in the Administration Building – First Floor. Our address is 304 E. Grand River, Suite 101, Howell, MI 48843. The Administration Building is directly east of the Historic Courthouse.

Maps are printed from Noon – 4:30 pm each day.  However, orders may be dropped off during the morning and the map(s) will be printed in the afternoon.  Map orders can also be submitted to the Mapping Technician via phone (517.548.3230) or fax (517.545.9608).

Can the maps and/or data be shipped?

Yes. The hard copy printouts and digital data can be sent to the customer, but shipping costs are an extra charge.

Can we print maps of other areas in Michigan?

No. We only have data for Livingston County. However, many other counties also have GIS programs. Contact the individual county to find out if they have a program similar to Livingston County.

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Are the data layers available in digital format?

Yes. The images are available in TIF or MrSID format. TIFs can be viewed using any image viewing software such as Internet Explorer or Netscape. MrSID images or TIFs are mainly used in GIS or CAD software designed to view the images. Any user who has AutoCAD 2002 or later version can use the MrSID images. We most commonly provide the images in TIF format because people seem to be more familiar with that data format.

All other GIS layers are available in ESRI shapefile format. Shapefiles can be inserted into AutoCAD or can be viewed in a variety of GIS programs including ArcView, ArcInfo, ArcExplorer, AccuGlobe, etc

How much does it cost for digital data?

According to the Enhanced Access Policy, the orthophotography costs $100 per section or $1 per acre. It is more cost effective to buy an entire section if the request is for more than an 1/8th (80 acres) of a section. The cost of other GIS layers varies by layer (view our Digital Data Request Form for a list of available layers and fees).

Data are provided on CD or DVD media.  The digital media are an additional cost:

Media:	Cost:
Disk	$1
CD	$2
DVD	$4

Can GIS software read the digital version?

ArcGIS (ArcInfo & ArcView version 8 or higher) can view the MrSID images (no extension is needed). ArcView version 3.2 can also read the MrSID images when the MrSID extension is turned on. AutoCAD 2002 and higher can also read the MrSID images.

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