REMOTE SENSING BASED FOREST

INVENTORY

Blom Kartta Ltd.

10.06.2009

Aki Suvanto

BLOM

• Leading company in remote

sensing business in Europe

• Offices in 11 countries

• Revenue about 100 M€ (2008)

• Main products

– Aerial photography

– Laser scanning

– Mapping & Modelling

– Databases

– Navigation & Location Services

• Forestry related production in

Finland, Norway and Spain

Blom Kartta Ltd.

• Is one part of Blom group

• About 30 employees

• Offices in Helsinki and

Joensuu

• Main products:

– Aerial photography

– Laser scanning

– Cartography

– Forest inventory

• Long tradition in forestry sector

– First infrared images 1977

– First colour infrared images 1977

– First digital orthophotos in forestry

purposes 1995

– First laser scanning experiments 1997

– First digital aerial photographs 2005

– First experiments in forest

interpretation started in 2006

– Remote sensing based inventory

system as commercial activity since

2007

Inventory process

• Planning

• Laser scanning

• Aerial photography

• Measuring field reference data

• Modelling

• Segmentation

• Interpretation

• Create datasets to customer’s data system

By-products of inventory process

• Orthorectified aerial images

– If images are captured

• Updating the stand borders

– We are not digitizing those borders by hands but these are updated using

automatic segmentation which produce microstands

– Forester can use microstands to update old stand borders

• Accurate terrain and canopy height model

• It is possible to find new products and applications

– Analysing soil

– Use these two raster datasets to modify stand borders

Remote sensing based forest inventory

+ Estimation of forest characteristics is highly accurate and

objective

+ It is cost-effective method in large areas

+ No sampling, it covers the whole inventory area

+ Processing is highly automatic

+ It is possible to estimate and calculate results for large forest

areas very efficiently

- We can not predict all variables

- Fertility classes or define forest management proposals

- Nature conservation issues

- Rare flora, fauna or habitats

- Expensive method in small areas

Risks which relates to this method

1. Bad weather conditions in aerial photographs and laser

scanning

2. Restrictions from air traffic control

3. Short time period to capture aerial data

4. Errors in field plots locations or errors in field plot

measurements

5. Quality of laser scanning data and aerial photographs

6. How the field plots represent the actual inventory area

7. To perform this inventory process by several data providers

Example data

Field plots in example inventory area

Measuring field reference data

Reference plots in inventory area

Modelling and calculation

Modelling and calculation

Different modelling methods

• Single tree detection

– It requires more expensive laser scanning data because of higher density,

at least 3-5 pulse/m2

– This method has not tested in operative inventory process

• Regression based methods

– We can not predict tree species specific results accurately

– Still, it works quite well in total forest characteristics

• Non-parametric methods

– We can estimate several dependent variables

• Tree species and total forest characteristics

– It requires lots of field reference data

• Minimum is 500 field plots

– k-NN, k-MSN

Modelling and calculation

• Dependent variables of forest characteristics

– Basal area weighted mean diameter

– Basal area weighted mean height

– Number of stems

– Basal area

– Volume

– Dominant height

• Also we can estimate forest characteristics in saplings

– In Finland development class T2

• Predicting diameter distributions

• Theoretical wood assortments

– Log and pulp wood

• There is a chance to find new variables to describe forest

Calculation units

• The basic calculation unit is grid-cell

– Size could be eg. 16x16 meters

– The general principle is that the size of grid-cell is equal to size of field

reference plots

– For every grid-cell we calculate all desired forest characteristics

– Stand level results are generalized from the grid-cells which are inside

the single stand

– Grid-cells could be utilized directly in data system

Stand level generalization

Stand level results

Microstands

• It is a new generation product

• Microstands splits the forest inventory area as homogenous units

as possible

• In forested area, the size of microsegments is approximately 250

m2 – 1 hectare

• Segmentation of microstands is an automatic procedure

– No humans visual interpretation

• It could be restricted inside the certain area

– Forest property or some other area

• It is based on laser scanning data

Microstands

Microstands

Example of utilizing microstands.

Theme of total basal area.

Data transfer

Conclusions

• Remote sensing based forest inventory will increase its popularity

in forestry

• This method is very powerful tool in right hands

– It requires very accurate planning

– Powerful and good implementation

– Quality control for every processing stage

• The quality and accuracy of forest resources should become better

• It provides new products and applications

– Eg. microstands, accurate terrain and canopy height model

• Forester is still needed

– It is not possible to automatize all working routines

– Forest management proposals and counseling for forest owners

– Checking of deciduous species in forest.