LiDAR in Iowa!!!

Products from the 

Iowa Lidar Project 

2011 ASCE/ICEA Surveying Conference 

October 20, 2011 

Jim Giglierano 

Iowa Geological and Water Survey 

Iowa Geological Survey

This is your brain on NED….. 


This is your brain on Lidar….! 


LiDAR in Iowa!!! 

• USGS 2005 CSC-2 contract with Sanborn 

– Productized LiDAR 

– FEMA and Standard Product Specs: 

• 1.4 m postings 

• 18.5 cm RMS @ 95% confidence 

• 37 cm RMS in vegetation 

• 1 m horizontal RMS @ 95% confidence 

• 95% of vegetation: FEMA product; (90% - Standard product) 

• 90% artifacts: FEMA; (89% - Standard) 

• 95% outliers: FEMA; (90% - Standard) 

• 98% of buildings removed: FEMA Product; (95% - Standard) 

– Deliverables: ASCII x,y,z,i text files; LAS all return 

binary files 


Funding LiDAR in Iowa?!? 

Iowa Dept. of Transportation - $1.5M 

Iowa Dept. of Agriculture and Land 

Stewardship - $.57M 

Iowa State Office of USDA NRCS - $1M 

Iowa Dept. of Natural Resources - $1.23M* 

Total $4.3 M 

*Used State Revolving Loan Fund for Water 

Quality to make payments over 20 years** 

**Actually paid off after 5 years 

Probably another $500,000 of internal funds 

spent on processing 


Standard Product 

FEMA Compliant Product 


LiDAR Products for Iowa 

• Product delivered as 2 x 2 km tiles 

(36,424 tiles in state!) 

• Each tile will have around 1.5 million 

data points 

• Deliverable 1: ASCII text files with 

BARE EARTH x,y,z,i ~ 2 TB total 

• Deliverable 2: binary LAS format files 

with all data and returns (first, last, bare 

earth, intensities, classifications) ~ 3 TB 


LiDAR USERS in Iowa 

• Most users want X,Y,Z data for CAD 

– IDOT and County engineers 

– NRCS and IDALS conservation technicians 

– IDNR land acquisition and engineering 

Put XYZ data on public server (2x2 km tiles) 

http://www.geotree.uni.edu/lidarProject.aspx 

• GIS users want various products: DEMs, 

contours, slopes, shaded relief, structures 

and vegetation 


Autocad Users 

• Jim Krivachek (Fayette Co Engineer’s Office) 

ftp.igsb.uiowa.edu/lidar_ftp/Presentations/KrivacekLidar.pdf 

1. Acquire data from Geotree xyz ascii or LAS 

binary http://www.geotree.uni.edu/lidarProject.aspx 

2. Use free software to look at and extract bare 

earth from LAS files 

3. Use Corpscon to convert coordinate system from 

UTM to state plane 

4. Import into Autocad 


GIS - 1 st Generation Derivatives 

• 200 2x2 km tiles per block 

• 1 meter bare earth DEM and hillshade 

• 1 meter first return DEM and hillshade 

• 1 meter last return DEM and hillshade 

• 1 meter intensity image 

• All 7 grids = 15-20 Gigabytes per block 

• http://www.igsb.uiowa.edu/webapps/nrgislibx/ 


Bare Earth 

Bare Earth 

First Return 

Last Return 

Intensity 


Iowa Geological Survey 

Bare Earth DEM


Bare Earth Hill Shade


First Return Hill Shade


Intensity of all returns

Statewide Estimate: Derived 

GIS products ~ 20 TB 


Here’s the original TIN and point density 

and a profile across a small creek 


Here’s the 1 meter grid derived 

from the original TIN 


Now a 3 meter grid from the 

original TIN 


10 meter grid – notice the poor 

profile 


Compare that to the 30 NED from 

USGS 


Contours derived from 1m (red) 

and 3m (green) DEMs 


2 nd Generation Derivatives 

• 3 meter DEM (mean of 3x3 1m grid cells) – 

height in cm – each cell stored as 16 bit 

integer 

• 1 meter hillshade – in JPEG2000 format 

• 2’ contours – derived from 3 m DEM 

• Typical county – 436 MB + 301 MB + 403MB 

= 1.14 GB 

• It took us most of two years to figure this out 

• Also available with SDE and web services 


Lidar Elevation – 3 m DEM 



Lidar 1 m Hill Shade


Lidar 2 ft. Contours

Lidar 2ft. Contours on DEM 


Lidar 2 ft. Contours on NAIP Airphoto 


2’ contours over 1m hill shade 



Lidar Accuracy

Where to get lidar GIS 

derivatives for counties in Iowa 

• ftp.igsb.uiowa.edu/GIS_Library/Counties/countyname 


• DEM_3m_I_xx.img (get all plus zip) where xx is the county number 

• Contours_2ft_xx.shp (just get zip) 

• Hillshade_1M_xx.jp2 (get all plus zip) 

• These are all in UTM NAD83 meters 


Some Applications of Iowa’s 

Lidar Data 

• IDNR Approximate Floodplain Mapping 

- $15M over 5-7 years to complete 

statewide coverage 

• IDOT Bridge Design and Flood 

Modeling 

• IDNR Watershed Assessments – 

RUSLE2 models 

• IDNR Sinkhole mapping 

• OSA – Locating archaeological sites 


Approximate Floodplain Mapping Priorities 

4 

3 

1 2 

3 

4 


IDOT LiDAR Examples – 

Bridge Design/Flood Model 

• Who – David Claman 

• What – Elevation and flow distribution 

2008 flood 

• Where - US 65 bypass 

• How 

– FESWMS (Finite Element Surface Water 

Modeling System) 

• Why – Compare predicted to actual 

flood data 


LiDAR Example – Flood Model 



Sinkhole Mapping - NED 10 meter 

Depression features from soil survey data in yellow 


Sinkhole Mapping with Lidar – 

now that’s better 


Mormon Trail remnants – Union County, Iowa 


LiDAR and Lodges 

Office of State Archaeologist 

Shaded Relief LiDAR Image of 

Newly Discovered Earthlodges near Glenwood 


Lodge depression

Flood Plain Mapping in Iowa 


Response to 2008 Floods 

– Iowa Department of Economic 

Development disburses $15 million in 

CDBG disaster recovery funds for the 

purpose of developing new floodplain 

maps and updating and improving existing 

floodplain maps in the 85 Presidentially- 

Declared Disaster counties due to the 

Flood of 2008. ($150k / County) 


Where can the money be spent? 

• $15M HUD CDBG grant 

• Administered by Iowa DED 

and DNR 

• Supports floodplain mapping 

in the 85 counties declared 

federal disaster areas 

• “…to produce floodplain 

maps that meet FEMA 

technical standards and can 

be published as Digital Flood 

Insurance Rate Maps 

(DFIRMs).” 


Mapping Sequencing by calendar year 

2014 

2013 

2013 

2012 

2011 

2014 


• Calculate annual recurrence 

stream discharges 

• Calculations are based upon DNR 

statewide LiDAR dataset 

• LiDAR data are used to create a 3- 

meter-resolution digital elevation 

model (DEM) 

• DEM is processed to determine 

flow direction and accumulation on 

the land surface 

• Discharge Calculations 

– 2-, 5-, 10-, 25-, 50-, 100-, 200-, 

and 500-year flows 

– Based upon stream gage 

statistical analyses & singleparameter 

USGS regional 

regression equations 

Hydrologic Analysis 


Hydraulic Analysis 

• Calculate water surface 

elevations for flows determined 

from hydrologic analysis 

• Based upon capacity of the 

channel and floodplain to convey 

flood waters 

• HEC-RAS Hydraulic model 

– Developed using HEC-GeoRAS 

tools in ArcGIS software 

– 1-meter resolution DEM is used 

to more accurately depict 

channel and floodplain features 

measured by LiDAR 


Floodplain Mapping 

• Hydraulic model results are 

intersected with the 1-meter 

DEM to calculate flood 

depths and inundation 

extents 

• Work maps are created in 

ArcGIS for submission to 

FEMA 


Where to get Lidar for Iowa 

• For derivative GIS data 

• ftp.igsb.uiowa.edu/GIS_Library/Counties/countyname 


• For raw point data 

• http://www.geotree.uni.edu/lidarProject.aspx 


Questions? 

Answers….. 

Jim Giglierano 

(319)335-1594 james.giglierano@dnr.iowa.gov

LiDAR in Iowa!!!

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