6k views

### How to create an accurate Tissot Indicatrix?

A Tissot Indicatrix is useful method for communicating at a glance the kinds of distortion a given projection is prone to (in the figure below, each of the red circles occupies the same area). I've ...
11k views

### Dealing with data that spreads across UTM Zones?

I have data that spreads across two UTM Zones GDA/MGA94 UTM Zone 55 and 56. I have layers such as a cadastre, roads, pipelines etc where I want to store measurements like lengths and areas in metres ...
4k views

### Distance measurements across UTM zones: use geographic or planar approaches?

I have a survey grid spread across 3 UTM zones (36N, 36S, 37S). I want to find the nearest (or shortest) distances of the centroids of these grids to roads and various points between. It seems like ...
1k views

### An example Tissot ellipse for an Equirectangular Projection?

I am trying to calculate distortion of an equirectangular projection via Tissot indicatrices. I have tried following the directions on this post (among other things) but it is beyond my understanding ...
186 views

### Are perpendicular lines still perpendicular after converting from UTM zone 15 to 16 (or between two neighboring zones)?

I want to convert a square polygon that is close to the edge of UTM zones 15N and 16N. The polygon's coordinates are in UTM 16N, but it is spatially positioned in the UTM15 area. My question is that ...
1k views

### How much error in a transformation?

I've been working in GIS for about a year and have a functional grasp of Projections and Transformations from within ArcGIS (10.0). Geosoft Oasis is another program we use. In working with our data ...
4k views

### What is a good projection for the whole of China (with units in meters)?

I get some GPS results which lay in China with WGS84 coordinate system, and I need to choose a projection to reproject for. First I chooses the UTM projection, but I find the results lay in ...
523 views

### Changing projection for field calculator

I've just succeeded in getting the area of a polygon using field calculator. The polygon was drawn on a Google hybrid aerial photo. There are no units given in the calculation and I assume the area ...
240 views

### Is nearest search done on Euclidean plane accurate

I am writing a program which will find all the points within 1km. I am planning to to do this on a Euclidean plane as my database only supports Euclidean plane or sphere indexing (http://docs.mongodb....
408 views

### Albers Conic versus State Plane Zone in terms of accuracy?

I'm trying to determine if an Albers Conic (Alaska Albers) is suitable as a projection for a corridor 800 miles long by 50 miles wide, that goes from the north coast of Alaska to the south coast. ...
780 views

### How does the projection of a dataset affect the results of spatial analysis?

I am planning on conducting a multi-criteria-analysis with a number of different source datasets. A number of the datasets are found in different coordinate systems and projections. Do I need to ...
92 views

### how to calculate area if it is falling in two utm zones [duplicate]

I am using ArcGIS 10.1. How do I calculate an accurate area measure for a polygon, where portions of it are falling in two zones, i.e. UTM ZONE 44 & 45 (India)?
410 views

### Pseudo code to correct Geographic points for UTM Easting distortion on Web Mercator Projection

I have chosen to use a Web Mercator projection system for: Use of Tiling system for low memory usage Accessing only one site/area at a time Reuse of Google Tiles - for many sites In some cases I ...