envi viewshed

image and elevation model

toolbox -> viewshed analysis -> select image and elevation model

enter view range and height

mark camera location

camera coverage is displayed. double click on camera in view sources to modify individual

change annotation to polyline, view range to 5000m, view height to 100, point spacing to 10

draw a polyline, right click -> accept

enable show point spacing, points are shown along polyline with 10 pixels spacing

viewshed is calculated

draw a polygon around building

adjust view range, height, spacing

viewshed calculated

reference:

https://www.l3harrisgeospatial.com/docs/viewshedtutorial.html

航拍中国 吉林

安省的药剂师将有权开处方的常见疾病

从2023年1月1日起，安省的药剂师将有权为13种“常见疾病”开处方，患者无需去看医生。这13种疾病包括花粉症（hay fever）、鹅口疮（oral thrush）、皮炎（dermatitis）、红眼病（pink eye）、痛经（menstrual cramps）、胃食道逆流（acid reflux）、痔疮（hemorrhoids）、唇疱疹（cold sores）、虫咬和荨麻疹（impetigo, insect bites and hives）、蜱虫叮咬（tick bites）、扭伤和拉伤（sprains and strains）以及尿路感染（UTIs）。

envi time series

file -> preference -> change auto display method to cir

file -> new -> raster series -> load time series files

build up difference series is generated

view -> 2 vertical view. load soil vegetation series on the 2nd view

series manager -> show all sliders. link slides

series manager -> annotate -> date and time

click to move annotation, right click to change properties.

reference:

https://www.l3harrisgeospatial.com/docs/timeseriestutorial.html

envi vegetation index

load forest file

toolbox -> radiometric calibration ->apply flaash

toolbox -> flaash atmospheric correction -> select radiance file

select use single factor for all bands. enter sensor info and atmospheric model

data manager -> right click on reflectance file -> load cir

spectral profile of healthy vegetation

stressed vegetation

toolbox -> spectral index -> moisture stress index

brighter pixels indicate more water deficiency

right click on moisture stress file -> new color slices

change min to 1

red region shows trees under stress

toolbox -> forest health vegetation analysis -> select reflectance image

select forest health parameters

forest health classification. 1 and 2 show stressed area

stressed areas

reference:

https://www.l3harrisgeospatial.com/docs/hyperionvegetationanalysistutorial.html

envi burn indices

load post fire image

right click on postfire.dat -> new roi

rename to water. threshold -> select NIR band, set min 0, max 830, enable preview

save roi as .xml

file -> save as -> apply inverse water

masked post fire image

tools -> radiometric calibration -> select masked image -> change type to reflectance

reflectance image

load thermal band

toolbox -> radiometric calibration -> select thermal image -> change type to temperature

calibrated thermal image

toolbox -> layer stack -> select reflectance and calibrated thermal. resampling -> cubic

stacked image

toolbox -> spectral index -> select layer stacked image -> burn area index

output normalized burn ration and thermal from spectral index as well

create 2x2 window. drag and drop images in divided windows, link all

white area in burn index indicates burned area

black area in burn ratio and thermal indicate burned area

to calculate difference of burn ratio pre and post fire

toolbox -> band math -> enter expression -> add to list

select post and pre fire burn ratio as variables

delta burn ratio

burn severity vs delta burn ratio 

right click difference burn ratio image -> new raster color slice

add color to indicate severity levels

delta burn ratio with color slices

reference:

https://www.l3harrisgeospatial.com/docs/burnindicestutorial.html