FUSING IN CAD CAPABILITIES INTO GIS. BY HONEST S. O. U.

FUSING IN CAD CAPABILITIES INTO GIS.       BY HONEST S. O. U.              

ArcGIS as a GIS software lacks some cartographic capabilities for drafting of work. We are often left with converting/ exporting our GIS work into a CAD environment and after some modifications in CAD environment, the work is exported back to ArcGIS environment. GIS lacks some conventional cartographic signs and symbols and does not allow free sketching of such signs/ symbols, a times we make do with Adobe Illustrator and other softwares to aid us.        The question therefore is,  how can we fuse in CAD capabilities into GIS environment?  I found out a simple method of doing this. You can convert your shape file to CAD file. Without closing the ArcGIs, open the CAD file and do the necessary modifications on the CAD  work. Use layer plotting for all text files, signs and symbols so that they can come out as layers in ArcGIS. After all the modifications both the layout and adjustments in the digitized features (Point, Line and Polygon) .Save your CAD work and open your ArcGIS file which u minimized and you will find all the modifications on your ArcGIS.                      Cheers.

STEPS FOR CONVERTING YOUR ArcGIS SHAPE FILE TO CAD.                                    1.Goto ArcToolbox.                     
2.Select Conversion Tools.                                     3.Select to CAD. Select ,Export to CAD.           Under Input Features, (select the shape files you want to convert). Under Output Type( select the DWG- the AutoCAD version u want to save it),  Under output file(Select the folder you want to save it).                                           4. Select Ok and wait for the files to convert/export to CAD. When its successful, it pops out successful message on the ArcGIS environment

Create your own Shapefile in Arcgis

Create your own Shapefile in Arcgis

If you wish to map certain points of interest, routes, or polygons but cannot find a shapefile, you can create your own.  This tutorial explains the steps involved in creating and editing a shapefile.

Step 1:  Creating your Shapefile

Open ArcCatalog

Navigate to your project folder

From the menu, click File>New>Shapefile

Give your shapefile a name and select a geometry based on what type of features you are trying to draw

Use the Edit button to select the coordinate system that you are using in your ArcMap project

To have a full details on self training visit www.heroizutech.com.ng and request a copy of A-Z of Arcgis 

Step 2: Editing your Shapefile

Add your shapefile to your ArcMap project

Open the Attribute Table of your shapefile

 Using the Attribute Table Options button, use the Add Field button to add fields you want to keep track of.  For example, if plotting metro stations, you may want to add a field for the name or number of the stop.

Optional: Set the symbology of your fields now.  This will save time later when creating features.

Turn on the Editor toolbar by going to Customize>Toolbars>Editor

Click on the Editor button and push Start Editing

Make sure your shapefile is selected in the Create Features window on the right

The bottom of this window shows the different construction methods available for your shapefile.  Click on one to start drawing.  You’ll notice that your cursor turns into a cross.

Click on your map to place a vertex.  You can place multiple vertexes to trace a route on your map.

https://civli-engineering.blogspot.com/2019/06/create-drawing-template-in-autocad.html

When finished drawing, right click and select Finish Sketch, alternatively you can push F2

To edit the attribute table for the feature you just created push the Attributes icon on the Editor toolbar.

All the editable fields for the feature you just created will appear.  This way you can label your features as you create them

When you’re done creating features click on the Editor button on the Editor toolbar and select Save Edits, and then Stop Editing

The symbology of the shapefile you just created can be manipulated like any other shapefile

Tips

 The snapping tool allows you to create features more accurately.  It will cause your cursor to snap to vertices, edges, and other features that you have created.  This will allow you to accurately place points on routes that you’ve created, or create polygons that do not overlap or have gaps between them.  To turn it on go to Customize>Toolbars>Snapping and turn the tool on in the toolbar that appears.

You can only edit the values in the Attribute Table of your shapefile while in Editing is turned on.

However, you cannot create new fields in the Attribute Table while Editing is turned on.  Create fields before starting an editing session.

If you set your symbology for your shapefile before you start the Edit session ArcMap will automatically create templates for your construction tool.

How to Converting a .jpg map into a shapefile In Arcgis

Converting a .jpg map into a shapefile

First 

There is no direct route to convert an image into a shapefile format. Your jpg map has no spatial reference. You can load it into arcmap but it won't know where to put it. In order to tell arcmap where it belongs in space you have to provide geographic reference points, hence the term 'georeferencing'.

In ArcGIS this is done via the Georeferencing Toolbar, which is turned off by default. To turn it on you just right-click on a toolbar, look for Georeferencing and turn it on. Then you will use the 'Add control points' tool (first button after right of the combo box) to tell arcgis what points on the image correspond to points on a second data source that already has a spatial reference.

Here are the steps I recommend following:

1. Open a new arcmap document.
2. Load an existing, vector shapefile of the counties you are interested in
3. Load the jpg of the map you want to georeference
4. In the Table of Contents, right click on the map and select 'Zoom to Layer'
5. Click on the 'Add Control Points' button on the georeferencing toolbar
6. Find a point on the map that you can match to the shapefile you loaded in step 2 and click on it. I recommend finding places that are easy to identify such as intersections of major roads, sharp corners in boundaries, etc
7. Then click on the 'Previous Extent' arrow on the toolbar to zoom back to your shapefile and move the map so that you can see the point you picked in the previous step in the shapefile.
8. Click on the corresponding point in the shapefile. You should see your map appear in the vicinity of where you clicked. It may be very small, or it might be huge, don't worry, you'll fix that with the next step.
9. Now you are going to repeat the last two steps using a second point on the jpg map, preferably one that is relatively far from the first one, but just go with what you can for now.
10. Repeat the process a few times and try to get the jpg as closely matched to the shapefile as possible. You'll never get it 100 percent accurate, but you can get pretty close if you try. If something goes crazy and the map gets really distorted you can either start over entirely or delete the last control point you added using the 'View Link table' button on the georeferencing toolbar.

Then it's just a matter of either editing your existing shapefile or creating a new one using the jpg map as a background. You'll probably have to assign some attribute data such as "Damaged" or "County Name" to the polygons you draw but that is a whole other issue.

I'm sure it sounds complicated if you've never done it before but it's really pretty easy once you get your head around the concept. Just remember that there are three fundamental steps here 1) Georeference the jpg so your GIS knows where it is in space, 2) Create a new dataset from the jpg in vector format, 3) Use the attribute table from your new dataset to conduct your analysis.

Here are some links that may be helpful: Get A - Z of Arcgis text book from HeroizuTech Services Ltd

http://www.heroizutech.com.ng 

For the second phase you will have to create a new shapefile. You will use the editing tools inside arcmap to digitize the affected areas as new polygons.

1) Create a new shapefile. Open up arcCatalog and navigate to the folder you are working in. Right click and select New --> Shapefile...

2) Give your shapefile a name and under feature type select 'Polygon'

3) Click the Edit... button in the lower right and select the coordinate system you want to work with, this should probably be the same as the one used by the county base file you used to georef the map jpg.

4) Open your arcmap document with the georeferenced jpg map and add your new shapefile to the document.

5) Right click on your new shapefile in the Table of Contents, got to 'Edit Features' and select 'Start Editing'.

6) Now you can use the 'Create Features' window to digitize the affected areas on your jpg map. Make sure to save your edits often using the Editing Toolbar.

7) Once you have drawn/digitized over all the affected areas save your edits and click on the 'stop editing' button.

8) Right click on your shapefile in the table of contents and select 'Open Attribute Table'. In the window that pops up, click on the drop-down button in the upper left and select "Add Field"

9) Name your field 'Area' and select 'Double' under type.

10) You should see your new field show up as a column on the right of your attribute table, right click on its heading and select 'Calculate Geometry', choose area and the units you want, this will tell you the area of each of the polygons you digitized.

That should give you everything you need to show the affected areas on a map and calculated the total area. Again, if you need further details or more instructions these steps have been heavily documented all over the web and a search for 'arcgis create shapefile' or something similar will give you lots of results with pictures/video that will be more descriptive than my summary.

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Regarding your last comment: You should now have three items in your table of contents. One should be the jpg map you georeferenced, a second should be the county map you used to georeference the jpg map, and the third should be the polygons of affected areas you just digitized.

To make a map that you can export and use as an image or figure somewhere else (ie a report or webpage) you will need to switch ArcMap over to 'Layout' view. (Go to the 'View' menu and choose 'Layout View') This is where you can add items like a legend, north arrow, and scale (via the Insert menu). Once you have things looking the way you would like them go to File, Export Map..., and choose the location, format, and resolution for the file you want to export. Then you will have an image file of the map you just laid out that you can use elsewhere.

I realize those instructions are pretty bare bones - if you need more help than that then that should really be a separate question, or the focus on how to get my book A-Z of Arcgis 

Ground Control - aerial photograph Ground Control

Ground Control - aerial photograph

Ground Control

By: Haseeb Jamal SHALLOW

In order to produce an accurate map from aerial photograph it is absolutely necessary to established ground control. It consists in locating the positions of a no of pts. All over the area to be surveyed det their levels. These control pts short be such that can be easily identified on the photographs. Horizontal control is established by tiring or traversing. Vertical control is established through the use of ‘aneroid barometers’ or ‘Altimeters’

Applications of Air Photograph:

The practical uses of air photography are unlimited. Some of the application are listed below:

• Town and country planning and developed estate man agent and economic planning are used both maps based on air survey and individual photography’s.
• suitability of roads and rail alignments can be studied both for traffic flow an economy of construction.
• Forestry and geology both use air maps and photography for the study of nature of areas and changes that take place.
• Flood control planning can be based on air survey made at suitable intervals of time
• Air survey provides means of mapping large undeveloped areas of the world.
• For large scale engineering and redevelopment projects, reconnaissance can be undertake in to a large extend form air photograph.
• Survey for accessing damage due to earth quake, crop dieses can be quickly estimated from air photograph.
• Pollution effects form industrial wastes on land and water can be studied.

Tunnels:

Tunnels are constructed in order

• To meet the req of rapid transportation in big cities.
• To connect by shortest route, two termination separated by mountain.
• To reduce very steep grades.
• To avoid the excessive cost of mantaineice of an open cut subjected to land slides or snow drifts.
• To avoid the expensive acquisition of valuable built up land, tearing up pavements and holding up traffic for long periods in large cities
• When the depth of ordinary cutting exceeds 20m and the ground rises rapidly for a considerable distance after wards.

Chief considerations in location of a tunnel are

• If should follow the best line adopted to the proposed traffic.
• If should be most economical in construction an operation.
• Convenience Ingress (enter) and Egress (leave)

Tunneling involves the following operatios:

• Surface Survey
• Transferring the alignment under ground
• Transferring levels under ground

  SURFACE SURVERY:

This includes

• A preliminary survey by transit and staid for 2-3miles (3-4km) on either side of the proposed alignment.
• A plan (map) with a scale of say 1 in with contours drawn at 5m (20) intervals.
• Final alignment is selected form this plan.
• A detail survey of the geological information of strata as the cost of tunneling depends upon the nature of materials to be encountered.

The proposed route having been decided upon, the following pts require consideration.

1. Alignment of the centre line of the tunnel.
2. Gradient to be adopted.
3. Determination of the exact length of tunnel.
4. Establishment of permanent stations marking the line.

Control surveys for tunnel layouts are performed on ht surface joining the terminal pts of the tunnel is shown in figure (1).

Transferring the alignment under ground:

This is the most difficult and important operation in setting out a tunnel.

• Fix two timber beams C and D as shown in figure two across the top of the shaft near its edges perpendicular to the direction of tunnel and as far apart as possible.
• A threadlike is set up at a ground at a pre-determined station on a centre. Line mark one ground surface and another stations is again on the centre line itself.
• The centre line is very carefully set up on the beams preferably on the plates fixed on a beam and drilled with hole for suspending wires by repetition observing and averaging the result.
• From these pts two long penal wire with heavy plumb hobs 10 to 15 kg attacked to their lower edges or suspended down the shaft.
• At the bottom these plumb bobs are immured in bucket of water, oil etc to eliminate oscillation.
• Great care must be taken that wires and plumb bobs are hanging free. As a check the dist b/w the wires at the top and at the bottom of the shaft is to be measured and this should be the same.
• The line joining the two wires gives the dir of alignment under ground.
• The theodolite is transfer to the bottom of shaft and through the no of trails suspended wires.
• Now the alignment is marked on marks driven into the whole i.e, E drilled on the roof.

Transferring levels under ground:

Leveling on the surface is done in the usual way and the levels are transfer underground at the ends of the tunnel from the nearest bench mark.

In case of transfer of levels underground at the shaft. The steps involve are

• A fine steel wire loaded with weight of 5 to 15 kg is passed over a pulley (w) at the top of the shaft and is lowered into the shaft as shown in fig.3
• Tow fine wire AA and BB horizontally stretched at the top and bottom of the shaft rasp.
• The steel wired lowered into the shaft is so adjusted that it is in contact with both the wires AA and BB.
• The pts of contact are marked on a still wire by a piece of chalk or by some other marker.
• The wire is withdrawn form the shaft and is stretched on the ground.
• The dist b/t the two marks on he wire is measured using the measuring tape and this gives the level of the bottom of the shaft.

LATTIUDE AND LONGITUDE:

O = Centre of earth

N = North Pole

S = South Pole

Nos = Polar axis or polar diameter about which earth rotates.

A = Any point on surface of earth

The position of a place on the earth surface is specified by latitude and longitude. The semi circle ‘NAS’ passing through A and terminates by the Poles N and S is called Meridian of the place.

LATITUDE:

Latitude of a place is the angular distance measured from the equator towards the nearer Pole along the meridian of the place or latitude of any pt ‘A’ is angle or arc AA’’. Latitude can also be defined as the angular distance that the place is north or south of equator.

The earth sphere being divided into two hemispheres by the equator, the upper one containing the North Pole is called the northern hemisphere. While the lower one having the South Pole is called southern hemisphere. The place is said to have a north latitude if it is in the northern hemisphere and south latitude if it is in the southern hemisphere.

The latitude angle is meared (90) at the earth center. North or south from the equatorial plane. Latitude north of equator is considered positive and that south of equator negative.

LONGITUDE:

Longitude of a place is the angular distance b/t the meridian of a place and the standard prime meridian

Or

Longitude of any place ‘A’ is angle ‘LA’ measured in the equatorial plane b/t the standard meridian and the meridian through A.

Or

The meridian NGS passing through Greenwich England has been adopted internationally as the standard meridian. This meridian divides the sphere into two hemispheres. The longitude is measured from “O” to 180 either towards east or west. The west longitude is considered as positive and the east as negative. Longitude angles are measured at the earth centre east or west from the plane of ‘O’ longitude which has been arbitrary placed through green witch England.

Hence the position of place ‘A’ is completely specified by the latitude and longitude. These two terms give unique location of any pt on the earth. This system of geographic co-ordinates is used in navigation and Geodesy.

How do I georeference an image in ArcGIS?

Q: How do I georeference an image in ArcGIS?

Answer

Georeferencing is a process by which a raster dataset (image) without spatial reference can be matched with a layer that does have spatial reference. For example, this process would be helpful in the case of a user finding an aerial photograph in their map.

In ArcMap, add a reference layer to your map that would be helpful in matching points from the image (e.g. streets if you have an aerial photograph of a city) or a basemap (click the dropdown arrow next to the Add Data button)

Add the image you want to georeference.

Open the Georeferencing toolbar (Customize > Toolbars).

Zoom to the area you will use for georeferencing your image. Select Fit to Display from the Georeferencing toolbar dropdown menu to move the image closer to where it should be located.

Add control points using the button with two crosses connected by a line: 

Zoom to your image (right click on the layer > Zoom to Layer). Add a control point to a place that will be easy to find in the reference layer, such as a road intersection, bend in a river, administrative boundary, etc. Zoom in close on the control point site to maximize your precision.

Zoom to the reference layer, and add the second control point in the same geographical location. Zoom in close on the control point site to maximize your precision.

Repeat these steps using points from around your map. Very quickly your image will fit in the map.

When you are finished go to Georeferencing > Rectify to save a new raster dataset that retains the spatial reference.

Helpful hints:

In the Georeferencing dropdown menu, the Transformation options are helpful if your image necessitates more warping.

The blue lines between control points represent the residual (or, error). The View Link Table button in the toolbar allows you to look at all of the links you have made, see their respective residuals, and delete ones you think may be inaccurate.