COLOR ME ORTHOED

Gary Lobdell

Photogrammetric Account Manger

Certified Photogrammetrist

The Sidwell Company

COLOR ME ORTHOED

ORTHOS, NOW WHAT?

• Review of the Image 2005 Orthophoto Products

• DEM vs. DTM

• How Will I View Them?

• What Features Will I Be Able to Identify?

• Custom Image Displays

2005 ORTHO PROJECT

Image Products

• 1 Meter County Mosaic

•1 Ft Color Ortho (79 Counties)

•½ Ft Color Orthos (13 Counties)

• 1 Meter Color IR

Data Products

• Digital Surface Model (DSM)

• Digital Elevation Model (DEM)

2005 ORTHO PROJECT

Image Deliverables

Type & Resolution Format/Tiling

1 Meter County Mosaic MrSid – Single County Tile

1 Ft Color Orthos (79 Counties) TIF – SPC Grid Tiles

½ Ft Color Orthos (13 Counties) TIF – SPC Grid Tiles

1 Meter Color IR USGS Quarter Quadrangle (3.75 Minutes)

DATA PRODUCTS

DSM – Digital Surface Model• Auto-correlated Elevation Data• Includes Above Ground Features• 1 or 2 Meter Posting (Terrain Dependant)

DEM – Digital Elevation Model• Processed Subset of the DSM• Near Bald Earth Elevation Set• Can Support Generation of 5 Foot Contours

DEM vs. DTM

Digital Elevation Model (DEM)

• Simple or Generalized Model of Earth Surface

• Use is limited to its original intent

• May Contain Points or Points & Minimal Breaklines

Digital Terrain Model (DTM)

• Complex Model of Earth Surface

• Multiple Uses within the Accuracy Expectations

• Will Contain Points & Breaklines

WHAT CAN I SEE?

½ Foot Resolution

High Level of Detail Visible

Wide Variety of Uses

1 Foot Resolution

Good Level of Detail Visible

General Variety of Uses

1 Meter Resolution

Good for Big Picture Studies or Viewing a Large Area

What Scale Can I View?

½ Foot 1 Foot 1 Meter

Use Imagery At Its Optimal Scale

• The Optimal Scale Is Approximately 200 Times The Pixel Resolution• Can Often Be Viewed Up To 100 Times The Pixel Resolution• Match The Use To The Resolution And View Scale• Need At Least 4 Pixels To Represent An Identifiable Feature

WHAT SCALE CAN I VIEW?

½ Foot 1 Foot 1 Meter

Expected Range of View Scales

1”=100’ 1”=200’ 1”=650’ 1”=50’ 1”=100’ 1”=325’

GOT PIXELS?You Need Enough Pixels To

Identify The Object

A Car Is Approx 5 X 10 Feet

At ½ Foot Res – 200 Pixels

At 1 Foot Res – 50 Pixels

At 1 Meter Res – 3 to 8 Pixels

GOT PIXELS?Identifying Manholes

½ Foot 1 Foot 1 Meter

RULES DON’T ALWAYS HOLD UP

Power Lines Shouldn’t Be Visible

Are Fences Are Too Narrow?

RULES DON’T ALWAYS HOLD UP

CAN I COLLECT NY OWN DATA?

Data is Best Collected by a Service Provider

• Stereo (3D) Data Collection is Most Accurate

• Collected from the Original Photography

• Professional Data Technicians

Things Are Not Always Where They Seem To Be

• Only on a True Ortho are the Building Tops Over the Base

• Manholes are Not Always Visible

• Pole Locations are Very Often Obscured

CAN I COLLECT NY OWN DATA?

DATA STORAGE

Storage Requirements by Resolution

Image Set Per Sq Mi Tile Size Per Tile

1 Meter Color 8 MB County (MrSid) Approx 170 MB

1 Foot Color 84 MB 2500 X 2500 Ft 19MB

½ Foot Color 335 MB 2500 X 2500 Ft 75MB

If 2500 X 2500 Pix 19MB

VIEWING ORTHOS

Current CAD and GIS Software Will Have Image Viewing Capability

Built In Image File Viewers

• ESRI Products

• MicroStation

• AutoCad

Lizardtech Offers Free Viewers for MrSid Files

THAT SPECIAL PROJECT

Customize Your Imagery

• Court Cases

• Zoning Issues

• Land Use

• Environmental Issues

PROJECT SPECIFIC IMAGES

Select a Portion of an Image and Add Text

PROJECT SPECIFIC IMAGES

Create an Image Customized for Your Display