Questions tagged [scale-factor]

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How do I generate a grid where each cell is equal to 500 px at 1:250k scale?

I worked this out once but I forgot how I did it. Somehow the grid size created a whole number of cells. I have a map with the following extents: xmin = -20037508.3427892439067364 xmax = 20037508....
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Scaling polygons in vector grid around polygon centers in QGIS

I have a aerial image with a vector grid overlaid in QGIS. Is it possible to scale the individual polygons (scale all of them by the same size) around their individual centroids? For example, to cut ...
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Scale Factors application not working on GEE PyQGIS

I'm trying to load some Lansadt 7 Collection 2 images on a QGIS project trought the following script: import ee from ee_plugin import Map ecorregiones = ee.FeatureCollection('users/paullcfias/...
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Sizing Diagram pies by quantity

I am using QGIS Zurich 3.12. I have records for some 35 species. The records (by year), initially, relate to four (point) locations. Two of the points have records for most of the species. The other ...
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3 votes
2 answers
637 views

Issue with scaling factors for Landsat Collection 2 Level 2 data when calculating NDVI

I'm trying to calculate the NDVI for a scene, and I've downloaded Landsat 8 OLI/TIRS Collection 2 Level 2 data, which means it has already been processed to surface reflectance. The scaling factors ...
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How do I accurately resize a map to match the scale of the next map I want to build a bigger map from?

I have exported a group of maps that I want to tile together in Illustrator. Since the maps are not of the same scale I tried calculating the factors between each scale to the largest number of map ...
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3 votes
1 answer
276 views

Statistic for measuring (local) autocorrelation of ordinal data

I have a spatial data set with a bunch of variables in nine-level ordinal scale. I want to calculate (local) spatial autocorrelation for each of these ordinal scale variables. I've been using ...
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Is having rectangular cell sizes in a raster bad (after resampling)?

I used rasterio to scale a raster I have to a new resolution. It was at (5.0, 5.0) resolution, and I wanted to make it (15.0, 15.0). However, the resulting resolution is not square anymore. Here's ...
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Scale data upon WCS request?

I am serving a set of GeoTiffs through GeoServer. In order to save disk space I have multiplied my original 32 bit floating point data by a factor 1000 and then rounded to the nearest integer, so I ...
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1 answer
337 views

Relation between scale factor and standard meridians/parallels

Let's use transverse Mercator with a custom zone, with central meridian 30, the zone is 3 degrees wide at the equator, with a scale factor k=1, it means that the cylinder touching the spheroid along ...
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Using correct coordinate system in ArcMap? [duplicate]

Im doing fyp on sabah & saraawak map. it came without prj file. i manage projected it and its allign to each other. but now i think the map is too small. as in the whole continent is within few ...
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Scaling more than 1000 polygons in QGIS

I have more than 1000 polygons, but they do not have the correct size and location. I have a table with the correct coordinates (centroid) "x, y" and different scale factor for each polygon....
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1 vote
1 answer
868 views

add scalefactor and offset to NetCDF

I am converting some NetCDF files from Float32 to either 16bit or 8bit to safe space on a server. Since I Originally created these NetCDF using GeoTIFF´s this is where I apply the conversion before ...
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2 votes
1 answer
156 views

How can I scale a feature referring to the area? [duplicate]

I'd like to scale features with a scale factor. With the scale tool of the editor toolbar it is possible to define a factor but then every single line of the feature is scaled by this factor. However, ...
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721 views

PostGis Scaling for Polygons at a fixed center location

I need to enlarge/expand a 2D polygon at its fixed location (lat,lon) with a constant scale factor in order to retrieve the surrounding area with the same shape as the origin polygon. What PostGIS ...
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1 answer
276 views

Getting more details by zooming in web-client?

today I've setup a qgis server and web client on my windows machine. Here is my WebClient. Now I'd like to test out everything. I tried to zoom in to the map, but it just stops by 1:2257 . I need ...
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Standardizing layers in R?

I am using R to develop species distribution maps. Since I standardized my covariates during the modeling process, I needed to transform the country-wide data (i.e. riv) using the same values. I ...
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1 answer
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How do I get a specific scale/zoom level in the QGIS canvas?

I have a map project with CRS = NAD83 zone 13N. The canvas will zoom to 1:144,447, 1:288,295, 1:577,790, etc. The values in the dropdown, on the other hand are 1:100,000, 1:250,000, 1:500,000, etc. ...
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1 answer
1k views

How to call Legend end points of multiple layers published from Geoserver?

I have map services published from ArcGIS server being called from Angular- Leaflet app and we are displaying the legend (controlled through map controls) from https://pxxxx.com/arcgis/rest/services/...
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1 answer
649 views

QGIS 2.12.1 - Problem with Size Assistant in „data defined override“ Button - Error message

While trying out the Size Assistant feature I encountered a problem. I´m working with this csv Table: I tried to resize the Point Size based on the field „Anzahl Objk“ and to do this I went to „...
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826 views

reading raster without making QGIS apply the scale factor to the raster

Since QGIS multiplies the image with the scale factor when reading, it messes up the image if the scale factor is not properly defined to the data as QGIS expected. For example, I am reading MODIS ...
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1 answer
215 views

LAStools (3D Analyst) scale factor application

I'm trying to use the las2las (transform) module from the LASTools toolset to apply a scale factor to an LAS dataset. The problem is that the client wants us to apply the scale factor from a known XY ...
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Query to merge simplified polygons according to the map scale-factor [closed]

I'm trying to construct a view in PostgreSQL that simplify polygons according to the map scale-factor. Basically I was reading this thread http://linfiniti.com/2011/06/scale-dependent-generalization-...
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2 votes
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229 views

DPI Dependent OSM Tile Rendering

We have built an OSM Tile Server following the instructions at http://switch2osm.org/serving-tiles/building-a-tile-server-from-packages/ The tile server is rendering tiles, but the street names on ...
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1 vote
1 answer
1k views

Using a Local Datum Plane (LDP) scale factor within ArcMap?

I have a CADD drawing that uses a Local Datum Plane (LDP) scale factor of 0.99991199. When I add the drawing to ArcMap without taking into account the scale factor, the drawing appears to the east of ...
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7 votes
2 answers
10k views

Influence of the scale factor on the projection

I'm currently reading documentation about map projections to understand the source code of the Proj4 project. The scale factor is named in a variety of sources I read. This sources explained its ...
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147 views

Scaling features based on an attribute [closed]

I would like to scale polygon features by a specific factor I have calculated for each feature in a feature class. I know of the Scale tool, however it only allows for manual entry of a scale factor ...
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4 votes
2 answers
3k views

Easy way to render TileMill tiles in retina mode with Leaflet?

I have a few quick little map websites that run straight off TileMill, without pre-exporting. They usually have code like this: L.tileLayer('http://example.com:20008/tile/MyMap/{z}/{x}/{y}.png', {})...
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1 vote
1 answer
2k views

My class using ogr to calculate distance is returning incorrect results away from the equator

In an answer to this question ustroetz kindly provided some sample code for use of ogr to do lat/lon distance and point in polygon calculations. I've created a Python class based on his example to do ...
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3 answers
3k views

maxScale or minScale don't work in vector (from WFS) layer

var options = { projection: "EPSG:900913", displayProjection: "EPSG:4326", units: 'm' }; map = new OpenLayers.Map('map', options); ilceSinir = new OpenLayers....
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