/r/askgis

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A community for new and old GIS users alike to ask technical and career questions. We want to hear about your GIS homework, project, work endeavor, or career goals.

Ask for help with Geographic Information Systems issues like geodesy or spatial analysis.


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/r/askgis

4,679 Subscribers

1

GIS contract work

I have a long history of remote contract work in project management. I have a graduate certificate in Geospatial technology. I’m looking for recommendations on how to find GIS contract work?

Thanks

4 Comments
2024/11/08
16:29 UTC

1

Looking for mildly complex projects

I’m looking for an analytical project that I can do with QGIS. I’m working on a writing sample for some job and grad school application. Would love to use Arc or Arc pro, but I’m broke.

2 Comments
2024/10/29
14:04 UTC

1

Display XY Data vs XY Table to Point

Is the XY Table to Point function in updated versions of ArcGIS Pro the same as the Display XY Data function in older versions? I am working with ArcGIS Pro 3.3.2 but following instructions for an assignment that uses an older version of the software. I have tried to use "XY Table to Point", where the instructions call for "Display XY Data", and the fields are the same, but it will not let me input the .gdb that I need for the output feature class. Any insight would be very helpful as I am trying to relearn GIS after taking a hiatus from using it. Thank you!!

3 Comments
2024/10/17
16:53 UTC

1

GIS Storage System in Local Government

Hi, working at a local council in UK which used to use MapInfo tables. They are thinking of switching to qgis since MapInfo is pretty much outdated now. Also qgis is cost effective.

In terms of storing data which is downloaded from public sector, for public sector use such as Ordnance Survey mastermap etc, what is the best solution?

We have some Agol licenses. That would mean storing data on Esri servers though. Is that secure for government data? Any other problems with Agol for this purpose? It doesn't use credits does it if you store data on there mainly for viewing etc. Then back ups would be needed to be stored on our own servers like just in folders in file explorer? In which case what's the point of AGOL here?

I know arcgis enterprise would use our servers but, since we don't have that already, it could be costly.

Which leads me to QGIS, is there a solution with them which would meet our needs in terms of security/practical/cost? Qgis is free isn't it?

Is there a qgis equivalent to Agol or something kind of storage solution?

Any ideas about the best way to store a lot of GIS files?

1 Comment
2024/10/17
16:21 UTC

4

How would you calculate the volume of rural water bodies if the only surface data you have is LIDAR based?

We have 100+ rural water bodies we need to calculate the volume for. Our surface elevation data is LIDAR based so for ~70+ of them that had water in them when the LIDAR was flown we have a flat water surface return. For the ~30+ that are dry we can use the LIDAR data as a TIN to get the volume under a surface area polygon with the max pond height, but not for those that have water.

Any creative ideas?

Using: ArcGIS PRO with spatial analyst and 3d analyst

EDIT: I ran 0.5ft contours and turned them into polygons. Connected contours would be inside each basin and where the contours break would be the crest or spillway.

7 Comments
2024/10/10
22:04 UTC

2

Which projection to use for accurate polygon area calculation in ArcGis/ArcMap?

Philippines Mindanao WGS84 UTM 51N

2 Comments
2024/10/05
05:44 UTC

0

Is “wicket” a valid pronunciation of WKT?

2 Comments
2024/10/01
15:19 UTC

1

Arcgis Pro animation extent, preview?

Is there a way to preview the map extent in an animation to see where overlay objects will actually appear?

0 Comments
2024/09/24
16:05 UTC

5

A list of all web Mercator tiles at high zoom that are nothing BUT ocean?

For reasons that are not very interesting, I am trying to optimize space/etc. on a dataset of web Mercator tiles in z,y,x format, similar to what Google Maps uses for its raster tiles.

Each level of zoom (z) means that the tileset below it is as 2^z x 2^z in height and width. So for z = 11, that means there are 4,194,304 tiles — a lot! For z = 12 and z = 13, it becomes 16,777,216 and 67,108,864 respectively, and so if you had tiles that were even pretty small (say, 10-20 KB), that easily can add up to about 0.5 TB for z=12 and z=13.

But at zoom levels of 12 and 13, the ocean is mostly featureless. In my use case, I could get away with just not having tiles at that zoom level and having it default to whatever it had for z=11, and that would save a LOT of space.

But to filter those out would require knowing what tiles of z=12 and z=13 were nothing but ocean — no other land nearby.

Does such a list actually exist? I could imagine how could laboriously create such a thing, by just having a full tile set and analyzing it, but it would be ideal for me to a) not have to have it in the first place (because that is a LOT of space), and b) it would take quite some time to run the analysis on that number of tiles. So I am wondering if it already exists somewhere.

I could also imagine basically getting the coordinates of all landforms and running a function that would generate the list of "edge" tiles for each zoom level, and filling in the "in between" parts, but that would also be a geometric/geographic/code nightmare I would be happy to avoid if possible.

Apologies for the rambling — just wanted to make sure it was clear what I was looking for!

5 Comments
2024/09/17
21:00 UTC

0

Resources for learning defense orientated satellite imagery

I got a job working in the defense field, mainly working on building web apps for analyzing satellite imagery for defense purposes. Mainly on detecting objects/vehicles etc in images.

I have a background in the software field, but I'm totally new to this field. Can anyone recommend a book/resource to learn this stuff? Aka stuff like SAR imagery, graze angle, gsd etc, COGs

0 Comments
2024/09/15
01:15 UTC

1

Resolution of TIN in ArcGIS Pro

I am wondering how do I find the resolution of the TIN's I have created. First, I imported my LAS file of a model I made in reality capture which has (0.004204 units/texel). In arcgis I created a las dataset followed by las dataset to tin. To retain a high resolution for thinning type i chose 'window size' and thinning method 'closest to mean'. Then for thinning value I made several using various values to obtain really fine detailed TIN's and some that are not very detailed.
I am attempting to make TIN's at various scales of 10m, 1m 10cm and 1m.

How can I find the resolution of the created tin?
For example, when I check the properties tab under the source tab it shows the following:
Data Type Tin

Tin window .0030

Location C:\Users\thebe\Documents\ArcGIS\Projects\SubmarineTIN

Triangulation Method Delaunay Conforming

Version Current

Total Points 496441

Total Edges 2978577

Total Triangles 992859

Z Range -0.486199 - 12.477239

Z Unit conversion factor 1.000000

Vertical Units Meter

Top 45.902622 m

Bottom -35.672394 m

Left -7.819510 m

Right 11.384145 m

Projected Coordinate System NAD 1983 HARN StatePlane Hawaii 1 FIPS 5101 (Meters)

Projection Transverse Mercator

WKID 2782

Previous WKID 102261

Authority EPSG

Linear Unit Meters (1.0)

False Easting 500000.0

False Northing 0.0

Central Meridian -155.5

Scale Factor 0.9999666666666667

Latitude Of Origin 18.83333333333333

Geographic Coordinate System NAD 1983 HARN

WKID 4152

Authority EPSG

Angular Unit Degree (0.0174532925199433)

Prime Meridian Greenwich (0.0)

Datum D North American 1983 HARN

Spheroid GRS 1980

Semimajor Axis 6378137.0

Semiminor Axis 6356752.314140356

Inverse Flattening 298.257222101

0 Comments
2024/09/04
19:42 UTC

2

on demand transit gis mapping analysis

I am currently researching how on demand transit has been used and deployed in certain area by using GIS analysis, I prefer to provide the results of on demand transit travel patterns by displaying the expectation of results (shown as below as an example) and how can I achieve making such type of GIS map and legend in ArcGIS Pro ?

https://preview.redd.it/rjsn5yrzv7md1.jpg?width=856&format=pjpg&auto=webp&s=f478702f88d00fadcc5db15bdeaa8553e6544d85

0 Comments
2024/09/01
15:35 UTC

3

Removing attribute table field name in legend in ArcGIS pro

I knew how to do it in arcmap, but in arcpro it’s not as straightforward. It is. It the layer name, but the field name underneath of it that I need to get rid of.

3 Comments
2024/08/29
14:04 UTC

1

Intersect/Join error on ArcGIS Pro

Hello, I am new to using GIS and am at the end of the fundamentals course from Coursera, totally stuck on the last assignment. They provide counties and burn areas in California and we are meant to 1. Dissolve wildfire perimeters 2. Intersect dissolved perimeters and county layer 3. Use summary statistic to sum the area 4. Join result of summary stats to county area. I can do everything up to the join where my counties and countystatistic table now has a mismatched number of rows. These extra rows appear in the intersect attribute table and even if I delete the duplicates, the objectID between these tables does not match when the stats tool is used. San Francisco is missing and I cannot figure out how to get it to stay. I have retried from the start multiple times and watched many videos so help is very much appreciated!

https://preview.redd.it/1erzqlu5ughd1.png?width=2817&format=png&auto=webp&s=93655a6698415253daa19f6d8a89e91c2618d20c

https://preview.redd.it/u0wgmou5ughd1.png?width=1140&format=png&auto=webp&s=c52bfd891a92f861f7e4ae222e7c1a6188751835

1 Comment
2024/08/08
16:22 UTC

3

Find Shortest Distance Between Multiple Shapes to A Line

I have 50 properties within a mile of a new path being built. I want to get the exact distance from the closest part of the property to the path. What tools should I use?

3 Comments
2024/07/31
18:51 UTC

1

Asking for help: polygon to raster - creating empty output

Good morning everyone!

I am having some issues. I have a land use land cover tiff file that has a pixel resolution of 28. I also have a polygon of a watershed that I'd like to convert to a raster of the same pixel resolution so that i can use raster calculator later. However, whenever I try to run the polygon to raster tool I end up with an empty output. I think this has to do with the protection but I'm not sure. The projection of the tiff lulc is Nad 1983 and although the polygon was originally wgs 1984, I used the define projection tool to change the polygon to match Nad 1983. Whenever I click on the polygon to change in the polygon to raster tool, the pixel size it automatically corrects to is 0.0001. If I change that to 28, nothing gets created but if I leave it, the raster does get xreated. Is this a very simple fix that I'm not seeing?

To be fair, I haven't used GIS in 9 years before I jumped on this project.

Any help would be appreciated!

8 Comments
2024/07/19
15:53 UTC

1

Mosaic Vector Dataset?

Has anyone seen anything that will mosaic a very large dataset of polygons? This is to manage updates like tiles similar to large imagery mosaic datasets. I think it would be virtual but with exports to create new polygon datasets for different size HUCs for public use. This is not parcel data, this is agricultural field boundaries. Thanks.

2 Comments
2024/07/16
15:43 UTC

2

ArcPro Creat Features Dialog Box

The create features dialog loading box pops up after three points are placed when editing new points. And I have hundreds of points to place. Is there a way to have this go to like 10-15 points? It just seems odd to constant need to cause me to stop work for it to save points.

1 Comment
2024/07/15
15:07 UTC

1

Calculate total acreage for different land cover types within a feature layer

I have a land cover layer that I have clipped to a property boundary layer and I would like to make a table summarizing the total acreage for each land cover type within my property boundary layer.

What is the most straightforward way to do this? In the past, I've exported the attribute table for the clipped land cover layer and found the total acreages for each land type using excel but I feel like there's simpler way I can do this within ArcPro.

Thank you!!

1 Comment
2024/07/08
23:50 UTC

5

Affordable Laptop for ArcGIS

I just graduated college. So I am super broke. I spent all of college using library desktops. But now since I am graduated, I can't use arcGIS. So I was wondering if anyone knows VERY affordable options for a laptop to run arcGIS.

1 Comment
2024/07/05
23:40 UTC

6

How to stop ArcPro from converting a string to integer in a standalone table?

Pardon what is probably a very stupid question (and apologies if it's been addressed before - i couldn't find it). New-ish to ArcPro here (former occasional ArcMap and AGOL user), and feeling like an idiot after several lost hours of trying to import this table with a 5-digit number that I would like to preserve as string (concatenated state-county FIPS code) so that I can join data to an existing layer.

I've tried the import from .csv, .txt, and .xlsx formats; I've tried opening all of these files in Excel, ensuring that the field was stored as text, and re-exporting to new .csv docs -- regardless, the field imports as integer and dropping the leading zeroes that almost half of the values have. I've also tried adding double quotes to the beginning and end of the string - when I do this, ArcPro imports the whole string including the quotes.

Any advice welcome!

9 Comments
2024/06/22
00:59 UTC

2

Setting parameters in a tool using values from a table

I have to run forty different Fuzzy Memberships. Each one has different minimum and maximum values. Some have the same inputs and all have different outputs. I have been using iterator in ModelBuilder but can't seem to figure it out. Any idea of a way to batch this in the model without having to type everything out?

I've created a table with Unique IDs, input raster, minimum value, maximum value, and output location. Now I just need to figure out how to add it into the Fuzzy Membership tool.

0 Comments
2024/06/18
21:28 UTC

2

water catchment delineation issue with .xml file - with both hydro tools & spatial analysis tools

4 Comments
2024/06/11
00:20 UTC

2

Help! Polygon that follows terrain.

I need to draw a polygon shapefile that follows the terrain. Think of it like a block in a valley so it needs to follow the bottom and sides. Application if for RAMMS debris flow block release if that helps. I’m using Arc Pro. Any help is much appreciated

7 Comments
2024/06/07
01:31 UTC

3

Computing XYZ tile links for an ArcGIS tile server

I have access to an ArcGIS map server that states the following in the MapServer response:

 "tileInfo": {
  "rows": 256,
  "cols": 256,
  "dpi": 96,
  "format": "PNG",
  "compressionQuality": 0,
  "origin": {
   "x": -35597500,
   "y": 48953100
  },
  "spatialReference": {
   "wkid": 102110,
   "latestWkid": 2154,
   "xyTolerance": 0.001,
   "zTolerance": 0.001,
   "mTolerance": 0.001,
   "falseX": -35597500,
   "falseY": -23641900,
   "xyUnits": 10000,
   "falseZ": -100000,
   "zUnits": 10000,
   "falseM": -100000,
   "mUnits": 10000
  },
  "lods": [
   // [...] removed for conciseness
   {
    "level": 12,
    "resolution": 0.07464551054102107,
    "scale": 282.1242
   }
  ]
 },

What I'm trying to do is compute the tile URL given a coordinate, but I'm struggling to find documentation for how this should be computed in this case since the server seemingly specifies a custom origin, as well as a custom coordinate system of sorts (falseX, falseY, xyUnits).

https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames

https://help.arcgis.com/en/geodatabase/10.0/sdk/arcsde/concepts/geometry/coordref/basicprinciples/basicprinciples.htm

But I can't really make sense of all this. The OSM docs don't use EPSG:2154, nor a custom origin, and I'm unsure at which point the falseX/falseY should be added into the mix...

Any pointers would be greatly appreciated :) I'm not in this field at all unfortunately...

0 Comments
2024/06/02
13:31 UTC

1

Is GIS only ever used on physical locations and geography?

What examples exist of using GIS but without the 'Geo' aspect? What would be the method for creating a map of items that do not have a physical location (or where physical location isnt a relevant component of the map). I'm certain this is being done, and looking for the software being used, what the methods are called, and how locations are determined, since there is a not a physical truth

examples:

  • components in a computer network
  • social network relationships between people
  • cross-database table usage and linkages
  • ownership and shared ownership of businesess and partnerships
6 Comments
2024/05/19
15:02 UTC

2

Distribution mapping

Hello! Sorry if this doesn't belong here, but how do I create a map on the distribution for debris in an area? Rather, I am planning to produce a map which shows how many litter are there based on our gathered data at a specified point. However with multiple sampling points also takes place in different environments such that X number of sampling sites are in (a) coastal areas, and X number of sites in (b) riverine areas. Is it possible to create a map of all differentiated environments and their count without making it seem cluttered? Or should I create a separate map for each two environments?

1 Comment
2024/05/18
05:52 UTC

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