Streetscape-Class

Description

The output of strview_search family functions is constructed in this data format - A specialized data frame for streetscape package for initializing the object with streetscape data and extracting and decoding segmentation information of streetscape dataframe.

Fields

data

A data frame containing metadata of Mapillary street view images

epsg

A numeric epsg code

Methods

decodeDetection()

Regenerate a dataframe with decoded segmentation. 'detections' column will be updated and a new column 'segmentation' will be added.

download_data(path, items)

Download street view images (and segmentations in sf format if applicable)

get_mask(index)

Convert the semantic segmentation of a street view image from the StreetscapeDataFrame into sf polygons

gvi(level)

Calculate green view index (GVI) for each collected image by segmenting green pixels and quantifing the percentage in street view images. This method adds a new column of greeness percetage to the dataframe

mapPreview(maptype = "meta", fields = c())

Plot data points in an ineractive map view

Class Methods

Method list

• StreetscapeDataFrame$decodeDetection()

• StreetscapeDataFrame$gvi()

• StreetscapeDataFrame$get_mask()

• StreetscapeDataFrame$mapPreview()

• StreetscapeDataFrame$download_data()

Method decodeDetection()

Usage

scdataframe$decodeDetection()

Method gvi()

Usage

scdataframe$gvi(level = 1)

Arguments

level

numeric, indicating the resolution level of images for calculating the green view index. 1 - the 256px wide thumbnail; 2 - the 1024px wide thumbnail; 3 - the 2048px wide thumbnail; 4 - the original wide thumbnail. The default is level = 1

Method get_mask()

Usage

scdataframe$get_mask(index = 1)

Arguments

index

numeric, the row index of the dataframe of StreetscapeDataFrame class

Method mapPreview()

Usage

scdataframe$mapPreview(maptype = 'meta')

Arguments

maptype

character or character, specifying what type of information to be mapped: 'meta' - image meta, 'seg' - segmentation proportion, and 'gvi' - GVI".

fields

vector (optional), a vector of fields indicates the information of images to be included for the 'meta' map. The fields of 'id', 'is_pano', 'height', 'width', 'lon', and 'lat' are already included

Method download_data()

Usage

scdataframe$download_data(path = 'path/to/download', items = c('image', 'mask'))

Arguments

path

character, directory for downloading street view images or segmentation masks or both

items

character or vector, specifying what to download: 'image' - 'original street view image; 'mask' - semantic segmentation (sf objects in .geojson format)"

Class "StreetscapeDataFrame"

Description

"The output of strview_search family functions is constructed in this data format - A specialized data frame for streetscape package for initializing the object with streetscape data and extracting and decoding segmentation information of streetscape dataframe."

Extends

All reference classes extend and inherit methods from "envRefClass".

Fields

data:

Object of class data.frame ~~

epsg:

Object of class numeric ~~

Methods

download_data(path, items):

~~

get_mask(index):

~~

gvi():

~~

decodeDetection():

~~

mapPreview(maptype, fields):

~~

initialize(data, epsg):

~~

Author(s)

"Xiaohao Yang"

Examples

showClass("StreetscapeDataFrame")

available-field-and-filter

Description

available_field provides a list of available fields.

available_filter provides a list of available filters.

Usage

available_field()

available_filter()

Details

Field and Filter List

Value

dataframe, including field names and their descriptions.

dataframe, including filter names and their descriptions.

Note

More information about fields and filter at https://www.mapillary.com/developer/api-documentation

decode_detections

Description

convert Mapillary object detection into sf polygons

Usage

decode_detections(detections_string)

Arguments

Value

sf polygon

Examples

detection <- readLines(system.file('detection.txt', package = 'streetscape'))
streetscape::decode_detections(detection)

install_mvt

Description

install_mvt is a wrapped function of py_install in the reticulate package for installing the python package mapbox_vector_tile, which will be installed in a virtual environment - "r-mvt".

Usage

install_mvt(envname = "r-mvt", method = "auto")

Arguments

Value

None

streetscape dataframe

Description

streetscape dataframe

Usage

data(scdataframe)

Format

An object of class "StreetscapeDataFrame"; see see_streetscape_class().

Examples

data(scdataframe)

see_streetscape_class

Description

A function to call out help page of StreetscapeDataFrame

Usage

see_streetscape_class()

Details

see_streetscape_class

Value

No return value, called for side effects

Note

User can also directly use ?StreetscapeDataFrame

Examples

see_streetscape_class()

strview2qualtrics

Description

strview2rate: pack street views as a Qualtrics survey file that can be imported to Qualtrics platform

strview2pwc: pack street views as a Qualtrics survey file for pair-wised comparison

Usage

strview2rate(df, header, questions, choices, file)

strview2pwc(df, k, header, questions, file)

Arguments

Details

strview2qualtrics

For strview2rate(), the lengths of questions and choices must match. For example, when questions = c('1. To what existence you can feel pleasant if you were in this environment', '2. To what existence you can feel safe if you were in this environment'), choices could be list(c('Unpleasant', 'Less pleasant', 'More pleasant', 'Pleasant'), c('Unsafe', 'Less safe', 'Safer', 'Safe')) For strview2pwc, the choices are always c('left', 'right') for the coparison purposes.

Value

character if argument 'file' is not specified

character if argument 'file' is not specified

Examples

data('scdataframe')
header <- "Please review the following picture(s):"
questions <- c('1. To what extent you feel pleasant if you were in this environment',
              '2. To what extent you feel safe if you were in this environment')
choices <- list(c('Unpleasant','Less pleasant', 'Pleasant', 'More pleasant'),
                c('Unsafe', 'Less safe','Safe', 'Safer'))
txt <- streetscape::strview2rate(scdataframe, header, questions, choices)

data('scdataframe')
header <- "Please review the following picture(s):"
questions <- 'which one is more beautiful?'
txt <- streetscape::strview2pwc(scdataframe, k=1, header, questions)

strview_search

Description

strview_searchByGeo: Search for and download the meta information of street view images via Mapillary API (See detials) based on coordinates of a spatial point with a given distance or a bounding box.

strview_search_nnb: Search for the nearest (within 10m buffer) available street view images and download meta information via Mapillary API (See detials) given coordinates of a spatial point.

strview_search_osm: Search for street view images by sampling locations along the OSM road lines and download meta information via Mapillary API (See detials) given a bounding box.

strview_search_multi: Search for and download the meta information of street view images via Mapillary API (See detials) based on multiple coordinates

Usage

strview_searchByGeo(
  x,
  y,
  r,
  epsg,
  bbox,
  token = "",
  limit = 10,
  fields = c(),
  ...
)

strview_search_nnb(x, y, epsg, token = "", fields = c(), ...)

strview_search_osm(bbox, epsg, token, fields = c(), size, ...)

strview_search_multi(viewpoints, epsg, token, fields = c(), ...)

Arguments

Details

strview_search

To request an API token of Mapillary, please create your access token at https://mapillary.com/developer. For 'fields', one can review all available fields in this package by calling streetscape::field_list().

Value

For strview_searchByGeo(), a StreetscapeDataFrame returned combining a dataframe of the image information.

For strview_search_nnb(), a StreetscapeDataFrame with one-row dataframe will be returned if there is any available images near to the given point

For strview_search_osm(), a StreetscapeDataFrame that combines the information of street views from all sampled points along the OSM lines within the specified bounding box.

For strview_search_multi(), a StreetscapeDataFrame that combines the information of street views based on the coordinates of multiple spatial points

Note

If there is no street view images within the search area, the function only returns an integer 0.

See Also

available_field() available_filter() see_streetscape_class()

Examples

bbox <- c(-83.751812,42.272984,-83.741255,42.279716)
if (isTRUE(file.exists("streetscape_token.sysdata"))) {
 data <- streetscape::strview_searchByGeo(bbox = bbox,
                                          epsg = 2253,
                                          token = "",
                                          is_pano = TRUE)
 data <- streetscape::strview_searchByGeo(x = -83.741289,
                                          y = 42.270146,
                                          r = 100,
                                          epsg = 2253,
                                          token = "",
                                          is_pano = TRUE)
}



if (isTRUE(file.exists("streetscape_token.sysdata"))) {
 data <- streetscape::strview_search_nnb(
         x = -83.743460634278,
         y = 42.277848830294,
         epsg = 2253,
         token = '')
}


bbox <- c(-83.752041,42.274896,-83.740711,42.281945)
if (isTRUE(file.exists("streetscape_token.sysdata"))) {
 data <- streetscape::strview_search_osm(
         bbox = bbox,
         epsg = 2253,
         token = '',
         size = 100)
}


x <- c(-83.752041, -83.740711)
y <- c(42.274896, 42.281945)
viewpoints <- cbind(x, y)
if (isTRUE(file.exists("streetscape_token.sysdata"))) {
 data <- streetscape::strview_search_multi(
         viewpoints = viewpoints,
         epsg = 2253,
         token = '')
}